Objective To explore the social function difference and influence factors of the only child and non-only child depression patients in youth. Methods The general demographic profile of 82 patients who met the criteria of depressive episode of Diagnostic and Statistical Manual of Mental Disorders（ DSM-Ⅳ） were collected. Hamilton Depression Scale（ HAMD-17）， Social Disability Screening Schedule（ SDSS）， Family Burden Scale-Disease（ FBSD） and a self-designed questionnaire were applied in the investigation. Results The scores of non-only child group in total social function defect， parent function and too little activity in the family were （11.06±4.04）， 0.00（0.00，2.00） and 1.00（1.00，2.00）， which were all higher than those of the only child group， and the differences were statistically significant（ P＜0.05）. Stepwise regression analysis indicated that father's education level， whether have child， family structure， health of family members may be the main influencing factors of social function. Conclusions The social function impairment in non-only child patients with depressive disorder may be more severe than only child patients. Father's education level， whether have child， family structure， health of family members may be the main influencing factors of social function.