Objective To explore the mediating effect of perceived social support on the relationship between perfectionism and depression. Methods 454 college students completed Almost Perfectionism Scale Revised Chinese Revised, Perceived Social Support Scale and Beck Depression Inventory. SPSS 12.0 was used for Spearman Correlation Analysis and Lisrel 8. 70 was used for Structural Equation Model Analysis. Results The model(M1) fit indexes of perceived social supports partial mediating effect on the relationship between discrepancy and depression were χ2/df = 2.15, RMSEA = 0.049, SRMR = 0.068, NNFI = 0.97, CFI = 0.98, IFI = 0.98, PNF1 =0.74, ECVI =0. 35. The model( M3) fit indexes of the relationship among high standard, discrepancy, perceived social support and depression were χ2/df = 1.77, RMSEA = 0.040, SRMR = 0.059, NNFI = 0.98, CFI = 0.98, IFI = 0.98, PNFI = 0.76, ECVI = 0.48. The two models were proved well. Conclusions Perceived social support partially mediates the relationship between the negative component of perfectionism and depression; The positive component of perfectionism moderates the relationship between the negative component of perfectionism and depression; Considering the effect of the positive component of perfectionism, perceived social support still partially mediates the relationship between the negative component of perfectionism and depression; To change the perceived social support of level may help perfectionistic individuals to decrease their depressive level.