Objective To observe the visual field loss after 577 nm krypton pan-retinal photocoagulation (PRP) in the treatment of diabetic retinopathy (DR). Methods A prospective clinical studies. Forty-six eyes of 26 patients with proliferative DR (PDR) and severe non-proliferative DR (NPDR) diagnosed by clinical examination from No. 306 Hospital of PLA during January 2014 and December 2015 were included in this study. Among them, 21 eyes of NPDR and 20 eyes of PDR; 13 eyes with diabetic macular edema (DME) (DME group) and 28 eyes without DME (non-DME group). All eyes underwent best corrected visual acuity (BCVA), fundus color photography, fundus fluorescein angiography (FFA) and optical coherence tomography (SD-OCT) examinations. The visual field index (VFI) and visual field mean defect (MD) values were recorded by Humphrey-7401 automatic visual field examination (center 30° visual field). The BCVA of DR eyes was 0.81±0.28; the VFI and MD values were (89.8±8.4)% and −7.5±3.85 dB, respectively. The BCVA of the eyes in the without DME group and DME group were 0.92±0.20 and 0.57±0.27, the VFI were (90.86±7.86)% and (87.46±9.41)%, the MD values were −6.86±3.43 and 8.87±4.48 dB. PRP was performed on eyes using 577 nm krypton laser. The changes of VFI, MD and BCVA were observed at 1, 3, and 6 months after treatment. Results Compared with before treatment, the VFI of DR eyes decreased by 12.0%, 12.3% and 14.8% (t=7.423, 4.549, 4.79; P＜0.001); the MD values were increased by −4.55, −4.75, 6.07 dB (t=−8.221, −5.313, −5.383; P＜0.001) at 1, 3 and 6 months after treatment, the differences were statistically significant. There was no difference on VFI (t=1.090, −0.486; P＞0.05) and MD value (t=−0.560, −0.337; P＞0.05) at different time points after treatment. Compared with before treatment, the BCVA was significantly decreased in DR eyes at 1 month after treatment, the difference was statistically significant (t=2.871, P＜0.05). Before and after treatment, the BCVA of the DME group was lower than that of the non-DME group, the difference were statistically significant (t=4.560, 2.848, 3.608, 5.694; P＜0.001); but there was no differences on the VFI (t=1.209, 0.449, 0.922, 0.271; P＞0.05) and MD values (t=1.582, 0.776, 0.927, 1.098; P＞0.05) between the two groups. Conclusion The range of 30° visual field loss is about 12%-14.8% after 577 nm krypton laser PRP for DR. VFI and MD can quantitatively analyze the and extent of visual field loss after PRP treatment.