Objective To investigate the effects of combination treatment of macular focal/grid laser photocoagulation and panretinal photocoagulation (PRP) on macular morphology and function in patients with severe nonproliferative diabetic retinopathy (NPDR). Methods Thirty-six eyes of 28 patients with severe NPDR were selected, and were divided into severe NPDR with clinical significant macular edema group (CSME group, n=20) and severe NPDR without macular edema group (NE group, n=16) based on the findings of best corrected visual acuity, fundus photography, fluorescein fundus angiography, optical coherence tomography (OCT) and MP-1 microperimetry. Combination treatment of macular focal/grid laser photocoagulation and PRP was performed in all included eyes, and examinations of best corrected visual acuity, OCT and MP-1 microperimetry were conducted 3 months after treatment. Results There was no significant change in best corrected visual acuity and macular thickness after treatment in two groups (P>0.05), there was no significant change in retinal sensitivity after treatment in CSME group (P>0.05), while the retinal sensitivity after treatment was significantly lower than that before treatment in NE group (P<0.05). Conclusion Combination treatment of macular focal/grid laser photocoagulation and PRP is effective in preventing macular retinal thickening in patients with severe NPDR and no macular edema, while it may cause visual function impairment.