Objective: To investigate the effect of different ultrafiltration volume and dialysate calcium concentration on serum calcium in pre- and post-hemodialysis in maintenance hemodialysis patients. Methods: Ninety-two patients were divided into Ca-1.25 group and Ca-1.5 group according to their dialysate calcium concentration, and they were divided into subgroups according to ultrafiltration volume respectively, A, B subgroups belong to Ca-1.25 group, and C, D subgroups belong to Ca-1.5 group, patients with ultrafiltration volume less than 3.0 kg were as subgroup A in Ca-1.25 group and subgroup C in Ca-1.5 group, patients with ultrafiltration volume equal or greater than 3.0 kg were as subgroup B in Ca-1.25 group and subgroup D in Ca-1.5 group. To measure serum calcium, serum phosphate and plasma parathyroid hormone (PTH) concentrations in pre- and post-hemodialysis respectively were detected and analyzed. Results: Serum calcium concentrations were higher in post- than that in pre- hemodialysis, the difference was statistically significant (P<0.01), variations of them were more obvious in B and D subgroups than those in A and C subgroups, the difference was statistically significant (P<0.01), and there were no significant differences in Ca-1.25 group and Ca-1.5 group, and in Ca-1.5 group they were higher than in Ca-1.25 group. Serum phosphate and PTH were no differences in A and B subgroups , C and D subgroups, and were higher in Ca-1.25 group than in Ca-1. 5 group, P<0.05. Conclusion: Calcium mass transfers from dialysate to blood during the hemodialysis using dialysate containing 1.25 mmol/L or 1.5 mmol/L calcium, ultrafiltration volumes are positively related with variations of serum calcium concentrations, but no relation with variations of serum plasma concentrations, and using dialysate containing 1.5 mmol/L calcium make patients more healthy.