Objective To observer the changes of chronic hemodialysis patients’serum Ca, P, iPTH and AKP when changed dialysate calcium concentrate from 1.75mmol/L(1.75CaD) to 1.5 mmol/L(1.5CaD) for 12 months. Methods This study includes 72 patients with normal pre-dialysis serum calcium and already using 1.75 CaD for 12 months. After changing to 1.5 CaD for 12 months, we measure these patients’iPTH, AKP, and pre- and post-dialysis serum Ca, P agein. Results When we changed dialysate from 1.75CaD to 1.5 CaD, we find pre- and post-dialysis serum Ca decreased significantly(P＜0.05 and 0.01 respectively), though pre-dialysis Ca-P product did not decrease, and we observed significantly increase in iPTH and AKP(P＜0.01 and 0.05 respectively). Conclusion For these patients with normal pre-dialysis Ca, changing dialysate from 1.75CaD to 1.5CaD could reduce pre-dialysis serum Ca level, and could increase iPTH and AKP.