Objective:To observe the risk factors of secondary neovascular glaucoma(NVG) after vitrectomy for proliferative diabetic retinopathy(PDR). Methods:A retrospective review was conducted on 288 eyes that underwent vitrectomy for PDR. Multiple factors were analyzed for their effect on secondary NVG using Fisher exact probability test. Results:Eight eyes(2.8%) developed secondary NVG. Fisher exact probability test showed that the P values of PDRⅥ,vitreous hemorrhage after vitrectomy and mutiple-surgery were 0.023,0.002,0.006 respectively. Conclusion:PDRⅥ,vitreous hemorrhage after vitrectomy and mutiple-surgery are main risk factors of secondary NVG after vitrectomy for PDR. Effective treatment at early stage of PDR and precaution of complications may reduce the incidence of secondary NVG.