Objective Bioelectrical impedance analysis has been widely used in clinical for detecting the human body composition. In this study, two kinds of human body composition analyzer were used to determine the body composition of cancer patients, providing a reference for the clinical application of human body composition analyzer. Methods Nutrition risk screening was used by NRS 2002, nutrition assessment was used by PG-SGA , and the body composition of cancer patients were detected by both IOI 353 body composition analyzer and BCA-2A body composition analyzer. The linear regression method was used to analyze the consistency between the indicators from two instruments, including body weight, body mass index, bone mass, visceral fat grade, muscle mass, basal metabolism, body fat rate, and body water rate. Results There were 110 cancer patients included, and 48 of them (44%) with NRS 2002≥3. Besides, 61 of them (56%) had a level of class B, and 31 of them (28%) had a level of class C of PG-SGA. The correlation coefficient of paired quantitative data between the two instruments was more than 0.975. There was a good correlation between the two instruments, and there was no significant difference in the analysis of paired quantitative data (P>0.05), showing difference is equivalent relationship between two instruments. Conclusions Cancer patients had a high incidence of nutrition risk and malnutrition. Nutritional risk screening and nutritional assessment should be carried out as early as possible, different instruments of human body composition analyzer showed good equivalence.