AIM:To explore the effect of pan retinal photocoag-ulation(PRP) on treating diabetic retinopathy(DR).METHODS:A total of 408 cases (795 eyes) of DR was chosen, 532nm semiconductor laser was used to have PRP, spot diameter was 300-500μm, time was 0.2-0.3 seconds,spot space was 1-1.5 spot. Slap shot 300-500 points per time to reach tertiary light spot; the amount of laser was 1 000-1 500 points, retreated for 3-4 times. The fundus fluorescein angiography (FFA) was performed 3-6 months after the treatment.RESULTS: Patients with obvious effect were 289 eyes (36.3%); with effect were 418 eyes(52.6%); with no effect were 88 eyes (11.1%), and the total effective rate was 88.9%. 234 eyes (29.4% ) had improved visual acuity, and 453 eyes had invalid treatment(57.0%).CONCLUSION: PRP is the most effective way for DR,and an important method to control the illness and protect the eyesight of the patient.