目的 揭示湿热环境下运动时机体的适应性，为训练提供理论依据。

Objective Based on the experimental study to the characteristics of organic composition of sweat changes in humid heat environment, the purpose to reveal people's physical adaptation ability of sport in humid heat environment and to provide the theoretical basis for the training. Methods We randomly selected 30 healthy volunteers from one university, whose average age was (21.3±1.1) years , without major diseases. The trialwas conducted in Humid Heat Environment Training Laboratory of The Second Military Medical University, at environment temperature 39℃, relative humidity 80%, training cycle 7 consecutive days, and training process in accordance with the principle of gradual and orderly progress. With Thermo Scientific iCAP 6000 Series ICP, we analyzed the composition of sweat collected during training and stored in the refrigerator. Rectal temperature was measured after training. Results Till the seventh day, the concentration of Urea,La,Na+,K+,and Cl- in sweat all declined from the first day(P<0.05). In addition to the concentration of La slowly declining on the sixth day, all others reached the minimum value on the sixth day, then there was an obvious trend of subsequent rise. Conclusions At least six days are needed for a hot and humid environment acclimatization training based on this trial design.