【Abstract】Objectve By investigated the calcium and phosphorus metabolism in peritoneal dialysis patients, to determined its causing and promoting factors. Methods Among 53 continued ambulatory peritoneal dialysis patients whose dialysis time was more than 6 months, serum calcium, phosphorus, iPTH had been assayed, and dialysis adequacy and intake of calcium element and phosphorus element from diet had been calculated. Results Elevated serum phosphorus level and multiplication of calcium and phosphorus were found in this group of patients. Serum calcium, phosphorus, and multiplication of calcium and phosphorus had positive relationship with dialysis time, residual renal Kt/V and CCr, carbon dioxide combining power respectively. (P less than 0.05 or 0.01). There were no relationship between serum calcium, serum phosphorus and dialysis Kt/V, dialysis CCr, intake of calcium and phosphorus from diet. (P large than 0.05 respectively). Conclusion Disorders of calcium and phosphorus metabolism, especially hyperphosporemia, are common feature in peritoneal dialysis patients. These disorders become more critical following the dialysis process. Decline of residual renal function take main responsibility of these disorders, and high calcium level in dialysate also involve in it.