Background and Objectives: Malnutrition, mainly caused by inadequate energy intake, predicts poor prognostic outcome in chronic kidney disease (CKD) patients. In this study, we aim to explore the effect of non-protein en-ergy supplement in CKD stage 3b-5 (CKD3b-5) malnourished patients with or without receiving continuous peri-toneal dialysis (PD). Methods and Study Design: 30 patients with CKD3b-5 and 20 patients who received PD were identified as malnourished according to Subjective Global Assessment (SGA), and enrolled into this clinical study. Compared with the control group which just received regular nutrition counseling, an additional non -protein energy supplement (600 kcal) was given to the participants for 12 weeks in the intervention group. Before and after study, the nutritional status of patients was judged by human body composition measurement, anthro-pometric parameters, physical fitness test, and quality of life survey. Other biochemical indexes relating to nutri-tion, renal function and inflammatory response were also included for disease evaluation. Results: After 12 weeks of oral non-protein energy supplementation, the body weight, body fat and associated anthropometric pa-rameters significantly increased upon intervention. Also, the participants showed enhanced physical fitness and better life quality in the intervention group. Consistently, the improved nutritional status was further confirmed by biochemical examinations. However, we did not observe a perceptible change of renal function, measured re-sidual renal function, or general inflammatory response indices after intervention. Conclusions: 12 weeks of oral non-protein energy supplement could efficiently improve the nutritional status of CKD3b-5 patients and those who receive peritoneal dialysis; meanwhile, it has little effect on renal function and inflammatory response.