Objective To compare the changes in refractive status after 25-gauge sutureless vitrectomy and 20-gauge standard vitrectomy. Methods One hundred and twenty-one eyes of 121 patients who presented with vitreoretinal disease were included in this prospective study. Patients were randomly divided into two groups, the A group, 61 eyes that underwent 20-gauge standard vitrectomy, and the B group, 60 eyes that underwent 25-gauge vitrectomy. Outcome measures included visual acuity, refractive power, and changes in corneal topography after surgery. Data were analyzed with chi-square test, independent samples t test, one-way ANOVA and Mann-Whitney test. Results The visual acuity of the B group was much better than that of the A group at one week and one month after surgery (x2=8.81, P=0.012; x2=65, P=0.036). The postoperative refractive error in the A group developed into hyperopia, then gradually returned to baseline at three months after surgery. The spherical and astigmatism powers for each timepoint were significantly different in the A group (F=530.12, P＜0.05, F=392.06, P＜0.05), but no significant difference was found in the B group. In the A group, changes of spherical power at 1 week, 4 weeks, 12 weeks after surgery were (+1.93±0.07)D, (+1.06±0.04)D, (+0.15±0.03)D, and changes of astigmatism power were (1.62±0.07)D, (1.05±0.05)D, (0.41±0.03)D. In the B group, changes of spherical power at 1 week, 4 weeks, 12 weeks after surgery were (-0.06±0.02)D, (-0.04±0.03)D, (-0.03±0.02)D, and changes of astigmatism power were (0.05±0.01)D, (0.03±0.01)D, (0.03±0.02)D. Change of spherical power between the A and B groups at 1 week, 4 weeks, 12 weeks after surgery was significant different (t=200.6, 159.3, 26.0, P＜0.01 for all), as well as astigmatism power (t= 173.4, 156.3, 82.3, P＜0.01 for all). At one week after surgery, corneal topography analysis showed that corneal SimK1-K2, surface asymmetry index (SAI), and surface regularity index (SRI) were significantly different compared to baseline (F=4.21, 3.44, 3.28, P＜0.05 for all). However, the changes in comeal topography before and after surgery in the B group were still statistically insignificant. The changes of SimK1-K2, SAI, SRI in A group were significantly more than that in B group (U=51.5, 45.5, 47.0, P＜0.05 for all). Conclusion Compare to a 20-gauge vitrectomy system, a 25-gauge transconjunctival sutureless vitrectomy system provides a more stable refractive status and better improvement in visual function postoperatively in vitreoretinal surgeries.