Objective  To investigate the factors relating to the variation of intra-abdominal pressure (IAP) in patients undergoing peritoneal dialysis (PD) and to explore the effect of IAP on PD therapy.  Methods  A total of 35 patients newly treated with PD were used as a study cohort. The Durand method was used to determine IAP. IAP was measured at the 3rd day after the surgery and after 6 months at a stable PD stage. The dialysate volume (PDV) was 2000mL when IAP was measured. Based on the mean IAP of 12.27±2.37 cmH2O at the stable PD stage, the patients were divided into group I (IAP ＜12.27cmH2O) and group II (IAP≥12.27cmH2O).  Results   ①The IAP at the 3rd day after the surgery was significantly higher than that at the stable stage (t=14.766, P＜0.001);  ②Body weight (t=-2.990, P=0.005), body mass index (BMI) (t= -3.838, P=0.001), and body surface area (BSA) (t=-2.277, P=0.029) were lower in group I than in group II, while total Kt/V (t=2.582, P=0.014), total Ccr (t=-2.450, P=0.014), residual kidney Kt/V (t=2.875, P=0.007), residual kidney Ccr (t=-2.583, P=0.009), and dialysis adequacy rate (P=0.044) were higher in group I than in group II.  ③Correlation analysis showed that BMI was positively correlated with the IAP after the surgery for 3 days  (r=0.558, P＜0.001) and after the operation for 6 months (r=0.688, P＜0.001). Linear regression obtained two equations: the IAP after the surgery for 3 days=0.425×BMI＋4.975 (r2=0.311, P＜0.001), and the IAP after the operation for 6 months=0.548×BMI-0.245 (r2=0.473, P＜0.001). ④ The IAP was significantly lower in the patients with adequate PD than in those with inadequate PD patients (t=-2.156, P=0.038).   Conclusion   ①IAP is significantly lower in the PD patients after the surgery for 6 months at a stable PD stage than in those after the surgery for 3 days. ②IAP variability is related to the characteristics of the patients, in which BMI is a factor closely related to the level of IAP. ③IAP is also closely related to the residual renal function of the patient. Maintaining IAP at a relatively low level will facilitate a higher dialysis efficacy at the early stages of PD.