Objective To investigate the relationship between the number of chronic diseases (NCD) and body composition of fat and skeletal muscle in the elderly population. Methods A total of 474 subjects aged 60 years and older who taking physical examination in a upper first-class hospital in Beijing from March to June 2017 were enrolled through the inclusion criteria in this study. The body composition was assessed by bioelectrical impedance analysis (BIA) and the NCD was investigated by the questionnaire survey. SPSS statistics 17.0 was used for data processing. Student’s t test was employed for intragroup comparison in measurement data. Spearman correlation analysis was adopted to analyze the correlation between NCD and each body composition index. Results The NCD had a highly positive correlation with age (r=0.75, P<0.01), but not with gender (r=-0.01, P>0.05). After adjustment of age and gender, the NCD had highly positive correlation with visceral fat area (VFA), body fat mass (BFM) of trunk and percent body fat (PBF) (r=0.71,0.61,0.60, P<0.01), and lowly positive correlation with BFM (r=0.21, P<0.01), but had no correlation with BFM of arms and legs (r=-0.06,0.03, P>0.05). While there was a moderately negative correlation between NCD and skeletal muscle mass (SMM), appendicular skeletal muscle index (ASMI), appendicular skeletal muscle (ASM), and SMM of trunk (r=-0.51, -0.50, -0.53, -0.53, P<0.01), a moderately or highly negative correlation between NCD and BMI, basal metabolic rate (BMR), protein and bone mineral (r=-0.60, -0.56, -0.42, -0.65, P<0.01), and a lowly positive correlation between NCD and waist-hip ratio (WHR) (r=0.23, P＜0.01). Conclusion NCD is closely correlated with age and VFA, followed by SMM, BMI and nutrition, but poorly correlated with BFM of arms and legs and WHR. The elderly should not only maintain the ASM of the lower limbs, but also focus on core muscle exercises to reduce visceral fat. At the same time, the elderly should pay attention to adequate intakes of protein and minerals.