Objective To investigate the changes of serum levels of 25-hydroxyvitamin D [25(OH) D] in ischemic stroke patients with post-stroke fatigue (PSF) and the intervention of vitamin D3 (VD3) on the rehabilitation of neurological function. Methods From January 2018 to December 2018 wereenrolled, 100 acute ischemic stroke patients who admitted to Affiliated Hospital of Chifeng University. Among them, 50 patients with PSF were divided as research group and 50 patients without PSF as the illness control group. 50 cases of healthy subjects were enrolled as normal controls (NC group). The general data of the three groups were statistically compared. The single factor and multivariate analysis were used to determine the risk factors of PSF. The research group was further divided into PSF-A group and PSF-B group, with 25 cases in each group, and group A was treated with VD3 for 6 months. The serum 25(OH) D level, FSS score, NIHSS score and FMA score were compared between the two groups. Results The NIHSS score and FSS score in the research group were higher than those in the illness control group, the FMA score and serum 25(OH) D were lower than those in the illness control group, the serum 25(OH) D levels in the research group and the illness control group were lower than those in the NC group, and the differences were statistically significant (P?