The present study is one of largest epidemiological studies about depression among Chinese university students. The study showed that the prevalence of depressive symptoms was 11.7%, and we diagnosed 4.0% of the sample as experiencing the Major Depressive Disorder. Steptoe et al. showed that Asian countries had the highest level depressive symptoms
, which was not consistent with our result. The incidence of depressive symptoms and Major Depressive Disorder in our study were both lower than in other studies, such as Bayram & Bilgel reported that depression levels of moderate severity or above were found in 27.1% of Turkish university students, Bostanci reported out of all university students in Denizli, 26.2% had a BDI score 17 or higher
. However, depressive symptoms are slightly higher than Nair's study which reported 3% among school/college students had severe and extreme grades of depression 
. These differences originated from different region, different measurement tools, different methods and different appraisal standards. University is an important transient life stage, with special academic, financial, and interpersonal pressures. Undergoing these transitions may lead to an increased risk of depression. However, the prevalence of depressive symptoms in the present study is a common incidence rate, similar to that seen in average people.
We found no differences in depressive symptoms between genders in our study. Similar to our results, some previous studies 
showed that no differences in depressive symptoms were observed among male and female students. This might originate from the fact that Chinese female university students have equal political rights, experience the same pressure, and face same job opportunities as their male peers. However, some studies findings are contrary to our results, and found higher levels of depression among female students 
We found that older students were susceptible to depression compared with younger students. This may be because the older students face more stressful events than the younger students, such as employment, economic, graduation, and marriage pressures. Contrary to our study, some studies showed that older students reported lower levels of depression 
We found little association between depressive symptoms and study year. Several studies showed that senior students had higher depression scores compared with freshmen 
, similar to our result. However, some studies showed that first- and second-year students have higher depression scores compared with those in the higher years 
. Dogan et al. found no difference in study year in terms of depression 
. These differences in findings might be explained by different measurement tools or sample errors. In recent years, college enrollment in China has expanded consistently. The workload and employment pressure of Chinese students are increasing. Many undergraduate students prepare for the postgraduate entrance exam just as they enter the university. Postgraduate students worry about employment from the beginning of their graduate life. These stresses could lead to the occurrence of depressive symptoms.
In the present study, we found that there was the significant association between the satisfaction with the major and depression. Students who were satisfied with their major had lower depression scores than those who were not satisfied. In China, students' major generally is determined by their parents. When a student doesn′t like his major, they have lower interest, passion and learning motivation in academic performance. Thus the dissatisfaction with the major could result in depressive symptoms. The same results were obtained from the study by Bayram et al. (7Bayram & Bilgel, 2008).
We found that students from poor families had higher depression than those from well-off families. Similar results were obtained by many other studies 
. Lorant et al. carried out a meta-analysis to evaluate the relationship between socioeconomic status and depression. Results indicated that persons in the lowest socioeconomic group have 1.81 the likelihood of depression compared with those in the highest socioeconomic group 
. Before Chinese economic reform, people's mental health was weakly influenced by people's economic status. This was because incomes were basically the same for all individuals. However, in recent years, China is in a transition period from a planned economy to a market economy, and it is now the case that individuals are given more pay for more work. It is increasingly the case that people's mental health is influenced by the economic conditions. This might be because economic conditions affect people's self-esteem and self-confidence. Low levels of self-esteem and self-confidence would lead to depressive symptoms.
A peculiar finding from our study was there was a negative correlation between the poor parental relationship and depressive symptoms. This result shows that the family environment affects students' emotional state. Parental relationships are the most important component in the family environment. China's special national conditions determine that there is only one child in one Chinese family. Most of parents try their best to love the only child. The poor relationship between parents could reduce the care of the child. The child's mental health is greatly influenced by the family environment.
Our study also found students with lower paternal education had higher depression. The educational level of parents is closely related to the students' mental health. Wu et al. found similar results in 2007
. Parents with higher level of education were able to pay close attention to students' psychological condition and actively communicate with students, which can increase students' psychological support. This is especially the case with the mother, as she is their children's first teacher and accompanies children more. The mother has a stronger influence over the children than father in China. A child could learn many behavior patterns from parents and be unconsciously influenced by parents' coping skills.
There were several limitations in the present study. The first limitation is the potential for sampling bias, as the sample in the study was only randomly selected from universities of Harbin. It is hard to generalize our findings to all Chinese students. However, we had a moderate sample size and used SCID interview to diagnose major depressive disorder. The second point is we only surveyed the depression distribution in university students and did not consider other psychological problems, such as anxiety. And the end sample size is small, further longitudinal, more accurate investigations are needed in order to confirm this merely preliminary report. However, the strategy of two step procedure of investigating the recognition of each specific diagnosed major depressive disorder that we used in our study should be improved. Another limitation of our study is that we had not considered family history of depression, stressful events, and social support. A future study may be required to examine the factors related to the genetic and environment variables.