Objective To explore the relationship between serum N-terminal pro-brain natriuretic peptide (NT-proBNP) level and hydration status and cardiac function indexes in the patients receiving peritoneal dialysis(PD) treatment，and to further analyze the factors affecting the level of NT-proBNP. Methods A total of 111 patients with PD who were followed up in the PD Center of Ruijin Hospital, Shanghai Jiao Tong University School of Medicine from May 2019 to January 2022 were enrolled and the data was analyzed retrospectively. According to the results of multi-frequency bioelectrical impedance body composition monitor (BCM), relative hydration status (DHS), the ratio obtained through dividing extracellular water (ECW) by overhydration (OH), the patients were divided into normal volume group (OH/ECW≤15%) and overhydration group (OH/ECW>15%). The relationship between serum NT-proBNP level and hydration status in two groups was compared, and the related factors affecting the level of NT-proBNP were further analyzed and discussed. Using BCM result as the“gold standard”, the receiver operator characteristic curve(ROC curve) determined the optimal threshold of NT-proBNP as the capacity was overloaded. The patients were divided into two groups according to NT-proBNP and their clinical data were compared. Results The indexes including systolic blood pressure, urine volume, urea clearance index (Kt/V), creatinine clearance rate(CCr), dialysate to plasma ratio for urea at 4 hours(4hD/PCr), types of antihypertensive drugs, type of diuretic, hemoglobin, serum albumin, log2(NT-proBNP), interventricular septal thickness (IVST), left ventricular posterior wall thickness(LVPWT), left atrial diameter(LAD), OH, TBW, ECW, OH/TBW, ECW/TBW and ECW/ICW were detected in volume overload group and normal volume group, and showed statistically significant (all P<0.05). log2(NT-proBNP) level was correlated with systolic blood pressure, dialysis duration, ultrafiltration volume, dialysis dose, antihypertensive drug group, IVST, LVPWT, LAD, left ventricular end-systolic dimension (LVESD), left ventricular end-diastolic dimension (LVEDD), OH, OH/ECW were positively correlated (all P<0.05). It was negatively correlated with urine volume, Kt/V, CCr, normalized protein catabolic rate (nPCR), hemoglobin, serum albumin and LVEF (all P<0.05). NT-proBNP 4 896 ng/L could be used as the critical value of initial screening capacity overload and was applied to divide the patients into two groups, and the systolic blood pressure, urine volume, ultrafiltration volume, Kt/V, CCr, IVST, LVPWT, OH/ECW indicators showed significant differences (all P<0.05) in two groups. Conclusions The level of NT-proBNP in PD patients is generally increased, and it indicates volume overload as its value is greater than 4 896 ng/L, which can be used as a simple monitoring index for the preliminary judgment of volume overload in PD patients.