Objective To compare the application value of different nutritional assessment tools for peritoneal dialysis patients. Methods A total of 147 patients who were hospitalized for peritoneal dialysis in The Second Affiliated Hospital of Naval Medical University between Oct. 2022 and Oct. 2023 were enrolled by convenience sampling method. The nutritional assessment was carried out by using 3 assessment tools, including 7-point subjective global assessment (7-SGA), malnutrition inflammation score (MIS) and controlling nutritional status (CONUT). Correlation analyses were conducted between the nutritional assessment results and anthropometric measurements and blood biochemical indexes. Results The incidence of malnutrition assessed by 7-SGA, MIS, and CONUT were 53.74% (79/147), 48.30% (71/147), and 76.19% (112/147), respectively. Both 7-SGA and MIS assessment revealed that the incidence of malnutrition in peritoneal dialysis patients ＞ 60 years old was significantly higher than that in patients ≤60 years old (both P＜0.01). Grouped by 7-SGA results, the body mass index (BMI), skeletal muscle mass, skeletal muscle mass index, phase angle, grip strength, upper arm circumference, upper arm muscle circumference, skinfold thickness, albumin and prealbumin levels in malnourished peritoneal dialysis patients were significantly lower than those in well-nourished peritoneal dialysis patients (all P＜0.05). The 7-SGA score was negatively correlated with age (P＜0.05), and was positively correlated with BMI, skeletal muscle mass, skeletal muscle mass index, phase angle, grip strength, upper arm circumference, upper arm muscle circumference, skinfold thickness, albumin, prealbumin, total protein, creatinine, and hemoglobin (all P＜0.05). Conclusion The incidence of malnutrition in peritoneal dialysis patients varies with the assessment tools used. 7-SGA score has high correlation with anthropometric and blood biochemical indexes, and is effective, reliable, and practical. It is a good tool for nutritional assessment in patients undergoing peritoneal dialysis.