Objective To evaluate the relevance of the macular hole index (MHI) and the visual outcomes of the idiopathic macular hole (IMH) after the retinal internal limiting membrane (ILM） peeling surgery.Methods Thirty IMH patients (30 eyes) undergoing vitrectomy and ILM peeling were included in this study. The IMH diagnosis was confirmed by best corrected visual acuity (BCVA), slit lamp microscope, indirect ophthalmoscope and optical coherence tomography (OCT). The central retinal thickness, the height and the base diameter of macular holes were measured by OCT. The MHI was the ratio of the height and the base diameter of macular holes. The patients were divided into two groups (MHIge;0.5 group and MHI＜0.5 group) according to the MHI.The post-surgery follow-up was three to 24 months with an average of 10 months. Spearman correlation analysis was performed between BCVA (pre and post-surgery), age, disease duration and MHI. The differences in BCVA after surgery between the two MHI groups was further evaluated by independent samplest-test for quantitative data.Results All the macular holes in 30 eyes closed after surgery, closure rate was 100%. Postoperative BCVA was correlated with MHI by Spearman analysis (r=0.852,P＜0.001), but not correlated with age (r=0.001, P=0.804) and disease course (r=-0.001,P=0.579). Postoperative BCVA was better in the MHIge;0.5 group (t=5.552,P＜0.001). Conclusions The postoperative visual outcome of IMH patients was correlated with the MHI. MHI can be used as a prognostic factor of postoperative visual outcomes for IMH patients.