【Abstract】 Objective To explore the related factors that associated with the Bone Mineral Den-sity（BMD）among the inpatients with schizophrenia，in order to provide better invention for osteopenia and osteoporosis. Methods Totals of 444 psychiatric inpatients with schizophrenia were selected from wards of the Tianjin Mental Health Center since January 2015 to July 2015. All participants were assessed by self-made questionnaire which included the socioeconomic status，past medical history，medications，dietary status and activity status，in addition of the clinical parameters，such as bone mineral density（BMD），serum prolactin（PRL） and blood calcium. All participants were divided into 3 groups according to the BMD，and the decision tree model was created to identify the influencing factors of the reduction of BMD. Results There were 300（67.57%） inpatients with decreasing BMD and 156（35.14%）with osteoporosis. “fracture history”was the first parent node of the model（χ2=46.347，P＜ 0.01）.“drinking coffee and strong tea”（χ2=55.424，P＜ 0.01）and“daily indoor activity” （χ2=31.191，P＜0.01）became the parent nodes on the second layer. On the 3rd layer，the nodes were “eating bean products”（χ2=35.801，P＜0.01）and“serum calcium concentration”（χ2=25.281，P＜0.01）. Conclusions The reduction of BMD among inpatients with schizophrenia is serious. The fracture history is quite significant forprevention of osteoporosis. For inpatients with fracture history，the moderate indoor activities are the protective measures. While for the inpatients without it，interventions on dietary are more meaningful in addition to surveil-lance of serum calcium.