Abstract: Vitamin D₃ is a kind of vitamin that plays important roles in maintaining the normal physiological function of the human body, and its metabolites and analogues exhibit strong anti-inflammatory activity. Vitamin D₃ could be activated and converted into 1α, 25-dihydroxyvitamin D₃, a kind of steroid hormone, in the human body, which participates in the regulation of cellular metabolism by activating vitamin D receptor (a kind of transcription factor), thus exerting immunomodulatory effects. This is essential for maintaining the physiological health of the body. Currently, there is a growing number of studies that suggest important roles for 1α, 25-dihydroxyvitamin D₃ in organ transplantation immunomodulation and tolerance. Therefore, we reviewed the overview and physiological effects of 1α, 25-dihydroxyvitamin D₃, the immunomodulatory effects of vitamin D₃ and the application of vitamin D₃ in clinical organ transplantation, and summarized the value of applying vitamin D₃ in inducing immune tolerance in transplantation, with the aim of providing a reference for promoting the application of vitamin D₃ in transplantation immunity.