The study found that the average age of undergraduates was20.92years,71studentsused diet pills, which was17.60percent.Theresultof the t-test found that self-discrepancy, family influence, and peer influence were statistically significant at a level of .05. According to the results of the backward stepwise binary logistic regression, the factors that were associated with diet pill usage at the high level were self-discrepancy and family influence. The sevariables were strong predictors of diet pill usage at60percent. More over,each question of the body image idea questionnaire was analyzed by using regression, found that skin complexion, facial features, muscle tone ,body proportion, weight, chest size,andphysicalcoordinationpredictedtheself-discrepancyofoverallappearance