Objective To investigate the effects of calcium and vitamin D ( Ca / VitD) supplementation on osteoclast activity and bone mass after hand and foot trauma. Methods Eight-week-old male mice were randomly divided into three groups: control ( C), Ca / VitD deficiency ( D), and Ca / VitD supplementary diet groups ( S). Group S underwent hand and foot trauma surgery after 8 weeks of standard feeding. Mouse serum analysis, micro-computed tomography (CT), histoeconometric analysis, immunohistochemical analysis, and gene expression analysis of fracture calli were used to investigate whether Ca / VitD deficiency could impair bone repair and cause bone loss after injury. The study also investigated whether Ca / VitD supplementation in the diet from the time of fracture could enhance fracture healing. Results Compared with the findings in group C, BMD and bone mass were significantly decreased in group D, whereas the fibrous tissue volume was increased. In the fracture callus, the number and surface of osteoclasts in group D were significantly enhanced. Compared with the result in group D, the bone mass in the callus was significantly increased in group S, whereas the amount of fibrous tissue was significantly decreased after Ca / VitD supplementation. In addition, group S exhibited a higher fracture healing rate. In group S, expression of the C-terminal telopeptide of type I collagen was decreased, whereas that of alkaline phosphatase and X-linked phosphate regulatory gene was increased. Meanwhile, the serum levels of iFGF23 and cFGF23 were significantly higher in group S than in groups D and C. However, the iFGF23: cFGF23 ratio was not different among the groups. Conclusions Ca / VitD supplementation after hand and foot trauma reduced osteoclast activity, increased bone mass, and suppressed bone absorption in mice with Ca / VitD deficiency. These findings should have guiding significance for clinical postoperative nursing.