Abstract: Objective:To explore psychological situation of the freshman students and the relationship of SCL-90 and DSQ.Methods:To conduct an investigation for 345 first-year students using SCL-90 and DSQ.Results:SCL-90 positive items and the scores of factors are significantly different to normal values(P<0.01) except somatization factor.The most common psychological defense mechanism are:expectations,sublimation,suppression,fantasy,avoidance,stop,relief,pseudo-altruism,split,tendency to contact.SCL-90 total score and total symptom index is closely related to the unmature or middle defense mechanism and is not related to mature defense mechanism.Only potential image,fantasy,projection,unity and complain enter the regression equation.Conclusion:(1)The mental health of first year students is different from that of the general population;(2)Excessive use of wrong defense mechanisms to cope with the conflict or frustration of daily life conflict or frustration will lead to a decline in the level of mental health.