Objective The aim of this study is to explore the correlation between vitamin D and diabetic nephropathy. Methods Relevant evidences were searched from PubMed, Embase, Web of Science, Ovid and China Knowledge Resource Integrated (CNKI), Wanfang Data Knowledge Service Platform databases (WANFANG), and VIP dating from inception to December 2019 to obtain the randomized controlled trials (RCTs) of vitamin D in the treatment of diabetic nephropathy. According to inclusion and exclusion criteria, two researchers independently screened the literature, extracted data, and evaluated the quality of included studies. Rev Man 5.3 software was used to conduct statistical analysis. Results A total of 10 studies involving 651 patients were identified. These studies were finally included into the meta-analysis. A meta-analysis results showed that vitamin D is the protection factor in diabetic nephropathy, the group treated with vitamin D did better than the traditional drug and the placebo group. After taking vitamin D, the level of vitamin D in the patient’s body increased significantly. Pooled results showed that there was a significant difference for vitamin D (MD = 38.24, 95%CI = 32.69–43.79, p < 0.001.) The patient had a significant decrease in urinary protein; the difference was statistically significant (MD = − 180.92, 95%CI = − 212.67 to − 149.16, p < 0.001). The blood creatinine content decreased obviously (MD = − 17.13, 95%CI = − 27.88 to − 6.37, p < 0.01). However, most of the included studies did not report the quality of life and adverse reactions of patients, making it impossible to analyze these measures. Conclusion This study showed that vitamin D played an active role in the treatment of diabetic nephropathy and can be used in future clinical applications. However, there are still some studies of low quality in the included studies, so it is suggested that clinical and scientific researchers carry out more high-quality, large sample, multi-center randomized controlled trials (RCTS) to provide more evidence-based medical evidence for future studies on vitamin D treatment of diabetic nephropathy.