Objective：The aim of this retrospective study was to investigate serum magnesium level in peritoneal dialysis（PD）patients in a single PD center and to compare the differences of demographics，dialysis status，and biochemical parameters among PD patients with different magnesium levels. Methods：This study analyzed the demographic characteristics as well as clinical and laboratory measurements of 147 patients in our dialysis center. These patients were divided into three groups according to serum magnesium concentration：group A：Mg2+<0.77 mmol/L，group B：0.77 mmol/L≤ Mg2+≤1.03 mmol/L，group C：Mg2+>1.03 mmo/L. Results：For serum phosphorus，serum calcium，serum potassium，serum urea nitrogen of dialysis patients：group A was significantly lower than group C；serum albumin：group B was significantly lower than that in group C；serum creatinine was significantly lower in group A than in group B and group C；for urea clearance index（Kt/V） and the standardized creatinine clearance rate：group B and group C was significantly lower than group A；The bivariate correlation analysis showed that serum magnesium was positively associated with serum phosphorus，and intact parathyroid hormone. Serum magnesium was also negatively associated with Kt/V and the standardized creatinine clearance rate. Moreover，our study found that the levels of serum magnesium were different in patients with different peritoneal transport characteristics which was divided by peritoneal equilibration test（P < 0.01）. Conclusion：There was an abnormal metabolism of magnesium in patients with PD. Among them，hypermagnesemia was more frequent than hypomagnesemia. Patients with lower serum magnesium concentration and high peritoneal transport capacity had better dialysis adequacy. Moreover，abnormal serum magnesium levels were often associated with other electrolyte and metabolic disorders. The levels of serum calcium，phosphorus and potassium may be higher and the serum glucose level may be lower in patients with hypermagnesemia.