Peritoneal dialysis is a kind of renal replacement therapy, which is mainly used in the treatment of uremic patients. There are many reasons for the decrease of ultrafiltration in peritoneal dialysis, firstly, it may be related to the decrease of the peritoneal function, which can be examined by peritoneal equilibrium test, to evaluate the function of the peritoneum. Secondly, it may be related to the concentration of the peritoneal dialysis solution, for example, if the peritoneal dialysis solution used is 1.5%, then it can be changed to 2.5% or 4.25%, and the amount of ultrafiltration will increase. There may also be a relationship with the infection of the abdominal cavity, because peritonitis is a relatively common complication of peritoneal dialysis, abdominal pain and cloudy peritoneal dialysis fluid may occur, you can check the blood routine, C-reactive protein and peritoneal dialysis fluid routine, to see whether there is bacterial inflammation and infection, according to the cause of the symptomatic treatment, you can increase the amount of ultrafiltration of peritoneal dialysis. Usually, we should also pay attention to oral diuretics, to retain a certain amount of residual renal function.