With the continuous development of social industry, the incidence of infertile couples has increased significantly. The percentage of couples of childbearing age who cannot conceive within one year is 25%, of which 50% are caused by male factors, and the trend is increasing year by year, causing a heavy economic burden and seriously affecting the quality of family life of the affected couple. The Jorgensen study found that 20% of young men had sperm concentrations below the World Health Organization’s recommended levels and 40% had sperm concentrations that did not reach optimal fertility levels. Up to 60-75% of male infertility patients have no known cause, but only quality abnormalities such as low sperm and weak sperm, and there is no definitive clinical treatment for this “idiopathic infertility”. Therefore, there is a great need to find an inexpensive, safe and effective treatment method. VD is a fat-soluble steroid derivative, which is an essential nutrient that cannot be synthesized by the human body, but can be taken from food or isomerized from 7-dehydrocholesterol in the skin by ultraviolet radiation. 1,25-(OH)2D is the active form of VD in vivo and exerts biological effects mediated by the VDR receptor. The traditional view is that its physiological functions are mainly to regulate calcium and phosphorus metabolism and promote bone growth, but since the 1990s, numerous studies have suggested that VD is closely related to male reproductive function. Animal experiments have confirmed that VD upregulates the expression of 19 testis-specific genes in mice through supporting the cellular ATP-binding cassette transporter protein A1 (ABCA1). Knockdown of the ABCA1 gene significantly reduced testosterone levels as well as sperm counts in mice.Blomberg et al. found that VDR and enzymes metabolized by it (CYP2R1, CYP27A1, CYP27B1, CYP24A1) were expressed in ejaculatory ducts, spermatogonia, mature spermatozoa, supporting cells, epididymis, seminal vesicles and prostate epithelium during spermatogenesis and maturation 1,25-(OH)2D induced an increase in intracellular calcium concentration in spermatozoa by acting on the VDR of spermatozoa, thereby enhancing sperm motility and mediating the acrosome response of spermatozoa. Aquila investigated the possible mechanisms of VD involvement in male reproductive function at the molecular level and found that 1,25-(OH)2VD acts on VDR and mediates cholesterol translocation from intracellular to extracellular via ABCA1, activates protein phosphorylation, elevates intracellular Ca2+ level, increases lipase activity, depletes The exact mechanism of VDR involvement in male reproductive function remains unclear, but available studies confirm that VDR is involved in male reproductive function at multiple levels, including genetic, sperm metabolism and function, testicular histomorphology and hormonal levels. As for how much dose of VD should be supplemented for male infertility patients to achieve optimal reproductive function, there is no uniform standard. In view of the recommended intake and safety of the Chinese Nutrition Society, 200 IU of VD per day was chosen in this study, but foreign scholars believe that at least 600 IU of VD per day is required to keep the body VD level from being deficient, i.e., serum 25(OH)D ≥50 nmol/l. It was also found that supplementation with 100 IU of VD per day can increase serum 25(OH)D by 2.5 mol/l. /Therefore, during the diagnosis and treatment of male infertility patients, the detection of serum 25(OH)D level should be paid attention to, and the corresponding VD dose should be given according to its level in order to make the 25(OH)D concentration to achieve the optimal level of fertility function.