Abstract: Vitamin D plays multiple crucial roles in human health, especially in bone meta⁃bolism and immune modulation. Obese patients generally confront the risk of vitamin D deficiency. Furthermore, bariatric surgery may further intensify the vitamin D deficient condition. The authors, in combination with relevant literature, conduct analysis and induction on the relationship between obesity and vitamin D, the influence of vitamin D deficiency on the immune system, the impacts of different bariatric surgery approaches on the vitamin D status, as well as the supplementation strategies of vitamin D, aiming to offer practical guidance and reference for the management of vitamin D after bariatric surgery.