〔Abstract〕 Objective To investigate the expression of macrophage migration inhibitory factor(MIF) and its effect on autophagy and insulin resistance of ovarian granulosa cells in polycystic ovary syndrome(PCOS). Methods Follicular fluid and ovarian granulosa cells were collected from 40 PCOS patients(n=40) and non PCOS patients(control group, n=20). PCOS included patients with IR(PCOS with IR, n=20) and patients without IR(PCOS without IR, n=20). The expression of MIF in follicular fluid was detected by ELISA. The ratio of autophagy vacuoles to microtubule-associated protein light chain Ⅱ(LC3Ⅱ)/microtubule-associated protein light chain Ⅰ(LC3Ⅰ)in granulosa cells was observed by transmission electron microscopy and Western blot. Human ovarian granule cell line KNG was cultured in vitro and CCK-8 was used to detect the effects of different concentrations of MIF on granule cell activity. KNG cells were divided into four groups: normal culture group(NC group), MIF group, chloroquine group(CQ group) and MIF+CQ group. The effects of MIF on the expression of autophagy related proteins LC3, autophagy related genes 7(Atg7), ubiquitin binding protein(p62), and insulin signaling pathway related proteins insulin receptor substrate-1(ISR-1), glucose transporter 4(GLUT4), protein kinase B(Akt) phosphorylation were observed by Western blot, and the effect of MIF on glucose uptake ability of granulosa cells was detected by glucose uptake test. Results Compared with the control group or PCOS without IR group, MIF expression in follicular fluid and autophagy level of granulosa cells in PCOS with IR group increased(P<0.05 or P<0.01); In vitro experiments showed that MIF could significantly inhibit the cellular activity of KNG in granulocytes in a concentration-dependent manner, in which 100 ng/ml MIF was selected for subsequent relevant experiments; Compared with NC group, LC3Ⅱ/LC3 I ratio and Atg7 protein in MIF group and MIF+CQ group increased(P<0. 05), while p62 protein, IRS-1 protein, Akt phosphorylation level, GLUT4 protein expression level and glucoseuptake ability decreased(P<0. 05), while the above autophagy markers in MIF + CQ group were significantlyhigher than those in MIF group(P<0. 05), and the protein related to insulin signal transduction and glucose up-take increased(P<0. 05).Conclusion MIF may promote IR development in PCOS patients by up-regulating theautophagy level of granulosa cells, while inhibiting the autophagy of granulosa cells can improve MIF-induced IR.