Objective To analyze the changes in visual acuity, regression of retinal neovascularization and flash electroretinogram amplitude after retinal laser photocoagulation for diabetic retinopathy (DR). Methods Prospective case-controlled study. The visual acuity, fundus fluorescein angiography, and f-ERG of 48 eyes with proliferative diabetic retinopathy (PDR) and 72 eyes with preproliferative diabetic retinopathy (PPDR) were analyzed and compared 1 week before retinal laser photocoagulation and 1 month after. Number of changes in visual acuity and retinal neovascularization and non-perfusion regression were counted. Amplitude of rod response b wave, mixed response b wave, oscillatory potentials, cone response b wave, and 30 Hz before and after retinal laser surgery were compared with a paired t test. Results For the visual acuity of PPDR patients, 48 eyes remained unchanged and 24 eyes decreased. For the same group, non-perfusion dissipated in 54 eyes, non-perfusion persisted in 16 eyes, and perfusion did not subside in 2 eyes. For the visual acuity of PDR patients, 12 eyes improved, 26 eyes remained unchanged, and 10 eyes decreased. For the same group, neovascular dissipated in 24 eyes, some neovascular persisted in 16 eyes, and did not changed in 8 eyes. Before retinal laser photocoagulation and post laser, the amplitude of rod response b wave of the eyes was (186.7±34.1)μV and (106.7±24.8)μV; the amplitude of photocoagulation mixed response b wave was (381.2±60.4)μV and (273.2±47.8)μV, the amplitude of oscillatory potentials was (66.6±12.4)μV and (86.6±18.7)μV, the amplitude of cone response b wave was (97.4±3.5)μV and (67.2±9.4)μV, the amplitude of 30 Hz was (24.1±8.4)μV and (20.1±6.4)μV, the difference was significant (t=5.672, 5.343, 3.427, 3.578, 2.979, P＜0.01 for all). Conclusion After retinal laser photocoagulation, the visual acuity of DR patients improved or remain unchanged, non-perfusion or neovascular dissipate in some patients, amplitude of most f-ERG wave derease except oscillatory potentials. So retinal laser photoeoagulation is an effective treatment for DR patients.