Diabetic retinopathy(DR)is a common microvascular complication of diabetes caused by chronic hyperglycemia and ischemia, which can seriously impair the patient's vision or even cause blindness. The main causes of visual impairment include macular edema, vitreous hemorrhage and neovascular glaucoma. Retinal laser photocoagulation is one of the most important therapies for DR. The thermal effects of laser photocoagulation can denature proteins, coagulate and destruct tissue, and finally scars occur. The scar tissue which consumes very low oxygen replaces the cones and rod and reduces tissue oxygen consumption significantly, and relieves the retinal ischemia and hypoxia especially for the middle and peripheral part of retina. However, complications such as macular edema, vitreous hemorrhage, and visual field defects may occur easily following laser treatment. This article reviews recent literatures about the complications and preventions of laser photocoagulation in DR treatment.