【Abstract】 Objective To study the effects of metformin treatment on serum asprosin levels in patients with polycystic ovary syndrome (PCOS). Methods 55 patients with PCOS in outpatient department and inpatient ward were selected from January 2019October 2019. All the patients were given metformin 0.5g/d for 3 months. Serum asprosin level, metabolismrelated blood biochemical indices and sexual hormone level were measured, and waisthip ratio (WHR), BMI, insulin resistance of homeostasis model assessment (HOMA-IR) and free androgen index (FAI) were calculated．The correlation between the change of asprosin level and other metabolic indices after metformin treatment was analyzed by linear correlation and multiple linear regression. Results The asprosin level ［(3.64±0.67)ng/mL vs (6.37±0.31)ng/mL，P＜0.05)］, BMI, fasting blood glucose （FBG）, triglyceride（TG）, fasting insulin（FINS）, HOMA-IR, testosterone（T）, Luteinizing Hormone（LH）, FAI were lower significantly and SHBG level were higher than that after metformin treatment. The decrease of the serum asprosin level of the PCOS patients was positively correlated with the decrease of BMI, TG, HOMA-IR and FAI. Stepwise multiple regression analysis showed that the decrease of HOMA-IR and TG were independent risk factors for the decrease of serum asprosin level in the PCOS patients（β=0.208, 0.810，P＜0.05）.Conclusion Metformin treatment can reduce the level of serum asprosin in PCOS patients, which may be related to improving insulin resistance and antilipemic effect. 