Abstract: Objective:To investigate the relationship between body height and fat free mass （FFM） in order to derive an approximation formula of FFM in healthy adults. Methods: 955 healthy adults were divided into obesity and non-obesity groups by BMI and into two groups by age of 45. Anthropometric measurements and bioelectrical impedance analysis （BIA） were done in the subjects. The impact of age and obesity on FFM was assessed. Nonlinear regression analysis was performed to assess the allometric relation of FFM and body height. Results: The values for FFM in healthy adults did increased with age and did not differ between obesity and non-obesity groups. The equations obtained by non-linear regression analysis that provided the best approximation of FFM for men were FFM （kg）=24.98×Height^1.68 and for women were FFM（kg）=22.84 × Height^1.42. Conclusions: The exponential of body height as a predictor variable were identified as appreciation of FFM.