Objective To evaluate the accuracy of bioelectrical impedance analysis （BIA） in measurement of appendicular skeletal muscle mass （ASM） of adults. Methods A total of 836 adults aged 18-42 years were recruited in Guangzhou using a convenient sampling method from April 2021 to September 2022. ASM was measured using BIA and Dual?energy X?ray absorptiometry （DXA）. Using DXA as the standard method， the consistency between the BIA and DXA measurements was evaluated by intra?class correlation coefficients （ICCs） and Bland?Altman analysis in logarithmically transformed data， in order to evaluate the accuracy of BIA in ASM measurement. Receiver operating characteristic curve was plotted to evaluate the diagnostic value of BIA for screening low muscle mass. Results A total of 774 individuals were included for analysis finally. ICCs for ASM measured by BIA and DXA were 0.774 and 0.667 in males and females， respectively. Mean ratios （limits of Agreement） of ASM were 0.94 （0.80-1.10） and 0.91 （0.78-1.05） in males and females， respectively. Area under curve of BIA for screening low muscle mass were 0.91 and 0.94 in males and females， respectively. The optimal cut?off values of Z?score by BIA for males and females were -0.57 and -0.66， respectively. Sensitivity and specificity for males were 82.5% and 86.0%， while being 86.8% and 93.8%， for females. Conclusion BIA shows a moderate consistency with DXA for measuring ASM in adults. Furthermore， BIA yields a good diagnostic value in identifying low muscle mass in adults aged 18-42 years.