Objective To study the relationship between adaptability improvement to hot-humid environment with the changes of rectal temperature, heart rate, and scores of comprehensive sensation before and after training in hot-humid environment. Methods Thirty healthy male university students were trained and tested under a temperature of 39.0℃ and a relative humidity of 80.00% for a week. Their rectal temperature, heart rate, and scores of comprehensive sensation were monitored every time before and after training. The obtained data were subjected to ANOVA analysis and Tukey-tests. The improvement rate of rectal temperature and improvement rate of comprehensive sensation scores were calculated each time after training in hot-humid environment. Results and conclusion We found that rectal temperature and scores of comprehensive sensation were consistent in demonstrating the improvement of the adaptability to hot-humid. It is suggested that rectal temperature and scores of comprehensive sensation should be used as reference standards for adaptability improvement to hot-humid environment, and heart rate is not recommended, but the combination of three indices should be used as safety control standard.