〔Abstract〕 Objective To investigate the factors influencing the pregnancy outcomes during frozen-thawed embryo transfer(FET) cycles in patients with polycystic ovary syndrome(PCOS). Methods A retrospective analysis was conducted on patients' data from 882 FET cycles. According to the pregnancy outcome, the patients were divided into non-implantation group(Group A), abortion group(Group B1) and live birth group(Group B2). Clinical data and laboratory parameters were compared among the three groups, and ordered Logistic regression analysis was used to study the factors influencing pregnancy outcomes after FET. Patients were also divided into four groups(C1-C4) based on the number of high-quality embryos obtained(0-3, 4-6, 7-10, ≥11), and their clinical data and laboratory parameters were compared. Results The clinical pregnancy rate, live birth rate, and miscarriage rate in the 882 treatment cycles were 71.09%(627/882), 61.68%(544/882), and 13.24%(83/627), respectively. Single-factor analysis showed significant differences in body mass index(BMI), infertility type, human chorionic gonadotropin(hCG) day estradiol(E2) level, number of retrieved oocytes, and number of high-quality embryos among Groups A, B1, and B2(P<0.05). Further multiple Logistic regression analysis revealed that BMI(OR=1.046,95%CI:1.001-1.093,P=0.044) and a history of previous pregnancy(OR=1.417,95%CI:1.030-1.950,P=0.032) were independent risk factors for successful FET in PCOS patients, while an increased number of high-quality embryos was an independent protective factor for successful pregnancy. Based on the results of Group B2, compared to Group A,OR=0.920,95%CI:0.880-0.962,P=0.000;compared to Group B1,OR=0.923,95%CI:0.862-0.988,P=0.022.Compared with the other three groups(C1-C3), the total amount of gonadotropin(Gn) in the C4 group was the lowest and the number of oocytes obtained was the highest(P<0.05). Multiple comparisons showed that Group C4 had lower BMI, follicle-stimulating hormone(FSH), very low-density lipoprotein(vLDL) levels, a higher luteinizing hormone and follicle-stimulating hormone(LH/FSH) ratio compared to Group C1(P<0.05). Group C4 had lower fasting insulin(FINS) and homeostasis model assessment of insulin resistance(HOMA-IR) levels compared to Group C3, and higher high-density lipoprotein-cholesterol(HDL-C) and apolipoprotein A1(Apo A1) levels compared to Groups C2 and C3(P<0.05). Conclusion BMI,the history of previous pregnancy and the number of high-quality embryos were both independent factors for predicting pregnancy outcomes in PCOS patients undergoing FET cycles. Patients with a higher number of high-quality embryos have a higher clinical pregnancy rate during FET cycles.