Objective To explore the impact of body mass index (BMI) on cancellation of embryo transfer (hereinafter referred to as cycle cancellation) due to preventing OHSS during controlled ovarian hyperstimulationin patients with PCOS. Methods This study was a retrospective cohort study. The clinical data of 719 patients with PCOS who were treated in our center from 2016 to 2018 were analyzed. According to the BMI (Asian standard), the patients were divided into four groups: low body weight group (BMI < 18.5 kg/m2), normal body weight group (18.5≤BMI < 24 kg/m2), super-combined group (24≤BMI < 28 kg/m2) and obese group (BMI≥28 kg/m2). They were divided into GnRH-a long program subgroup and GnRH-A antagonist program subgroup to explore the independent effect of BMI on cycle cancellation in each group. Results Compared to the underweight group, the multivariate regression analysis found that the obese group transplantation cancellation is significantly reduced (β3.61; 95%CI:0.84-15.54), while overweight group and normal weight group showed a reduced trend (OR2.33; 95%CI:0.56~9.75), (OR1.76; 95%CI:0.46-6.80). Compared to the underweight group, stratification analysis revealed that overweight and obese group treated with the GnRH-a agonist was significantly reduced (OR2.86; 95%CI:1.29-6.33), (OR2.77; 95%CI:1.16-6.63), while overweight group and obese group were showed a reduced trend also (OR2.31; 95%CI:0.65-8.25), (OR1.83; 95%CI:0.48-6.99). Conclusion Among the PCOS patients, the lower the BMI, the higher the cycle cancellation rate, and this trend is more obvious in GnRH-a agonist group. Thus, when choosing an COH protocol, in addition to the patient′s ovarian function, age, etc., female BMI is also a factor that needs to be considered.