In order to obtain the characteristics of the change of wettedness under constant average skin temperature 36 degrees C, the experiments were carried out using two young male subjects in a test chamber. From the basic measurements of both environmental parameters and human physiological responses, the authors found the wettedness value changeable even though the average skin temperature was constant. The following results were obtained under the conditions of resting-sitting, summer clothing worn, still air movement and constant average skin temperature 36 degrees C; 1. there is a positive correlation between wettedness and the environmental vapor pressure. 2. There is a negative correlation between wettedness and the air temperature. 3. There is a positive correlation between the evaporative heat loss from skin surface and the air temperature. 4. There is a negative correlation between the evaporative heat loss and the vapor pressure. 5. There is a negative correlation between wettedness and the evaporative heat loss. 6. Both maximum and minimum values of wettedness correspond to the average skin temperature. Considering the afore-mentioned results, the equal line of the average skin temperature does not form a straight line, but a curved line on the psychrometric chart.