Objective To investigate the effect of 25G vitrectomy combined with vitreous cavity injection of ranibizumab in the treatment of diabetic vitreous hemorrhage. Methods Retrospective case controlled study of 65 cases (71 eyes) with vitreous body resection for diabetic vitreous hemorrhage. The control group (35 eyes) received only 25G vitrectomy while the combination group (36 eyes) received an intravitreal injection of 0.5 mg ranibizumab five days before vitrectomy. The two groups were compared for operation duration times and the number of new blood vessels hemorrhages. Postoperative comparisons were made at 1 week, 1 month, 3 months, and 6 months for the recurrence of vitreous hemorrhage and best corrected visual acuity (BCVA). Statistical comparisons were made by independent samples t-test and chi-square test. Results The operation time for the control and combination groups were 94.5±21.3 min and 65.2±16.2 min, respectively (t=-7.005, P＜0.001). The average number of new blood vessel hemorrhages was 1.8±1.1 and 0.6±0.6, respectively (t=-4.686, P=0.001), and the frequencies of intraoperative coagulation were 1.1±0.8 and 0.4±0.6 for the control and combination surgeries respectively (t=-3.552, P=0.007). For the control group, the occurrence rate of intraoperative iatrogenic retinal hiatus (13%) was higher than for the combination group (4%), and the recurrence rates of vitreous hemorrhage for the control group at one week and one month after surgery were higher than for the combination group (χ2=3.92, 3.47; P=0.03, 0.03). BCVA improved rate in the combination group was higher than that in the control group in one week and one month after operation (χ2=6.27, 4.13; P=0.02, 0.03). There were no significant post-operative differences between the two groups for the occurrence of anterior retinal membrane, high intraocular pressure, or the incidence of the neovascular glaucoma. Conclusion Surgical 25G vitrectomy preceded by vitreous cavity injection of 0.5 mg ranibizumab five days before surgery reduced postoperative bleeding, shortened vitrectomy time, reduced the recurrence rate of vitreous hemorrhage, and improved visual acuity of the patients.