Abstract: This paper studies the effect of family background on mental health of college graduates. The data is collected from 5090 undergraduates in 2009 applied SCL-90 and self-compiled family background questionnaire. The results show that the difference of mental health scores is significant when measuring on the seven family background dimensions, such as whether the student the onlychild family or not, whether with experienced trauma or not, the family economic situation, family structures, atmospheres and parenting styles. Thus, the education of college students' mental health should pay attention to their family background. And the suggestions are as follows: 1) to put the demographic data form into students' files for mental health alert; 2) to bring the team of psychological counseling into full play; 3) to set up a system for communication between college and students' families.