Background Pars plana vitrectomy (PPV) is the main therapy for advanced stage of proliferative diabetic retinopathy (PDR).Intravitreal injection of anti-vascular endothelial growth factor(VEGF) drug before PPV for PDR has been proved to decrease the occurrence of postoperative complications.However,the effect of conbercept on PPV was rarely reported.Objective This study was to observe the efficacy of intravitreal injection of conbercept (IVC) on PPV for PDR.Methods A nonrandomized control clinical trial was performed.A total of 47 PDR patients (51 eyes) undergoing PPV were enrolled in Yuebei People's Hospital from June 2015 to May 2016.All subjects were divided into IVC group (24 patients,26 eyes) and control group (23 patients,25 eyes).The incidence of iatrogenic retinal hole,rate of using intraocular tamponade,incidence of postoperative complications,central retinal thickness (CRT) and the best corrected visual acuity (BCVA) were comparatively analyzed.Results The incidence of iatrogenic retinal hole in IVC group was 7.69％,lower than 32.00％ in the control group,the difference was statistically significant (P=0.038).The percentage of using intraocular tamponade in IVC group was 19.23％,lower than 52.00％ in the control group,the difference was statistically significant (x2 =5.993,P =0.014).Four months after surgery,the incidence of postoperative vitreous re-hemorrhage in IVC group was significantly lower than that in the control group,the difference was statistically significant (P =0.024).Three months after surgery,the CRT in IVC group was (278.04 ± 43.46) μm,which is thinner than (340.76 ± 84.91) μm in the control group,the difference was statistically significant (t =-3.340,P =0.002).Three months after surgery,the BCVA in IVC group was better than that in control group,with significant difference between the two groups (Z =-2.114,P=0.034).No adverse effect was observed after IVC.Conclusions IVC before PPV for PDR can reduce the incidence of iatrogenic retinal hole and the rate of using intraocular tamponade,decrease the incidence of postoperative complications and macular retinal thickness,and improve the visual acuity.