With melamine resin as the shell and with encapsulated phase change material and was applied paraffin as the core, a cooling vest was prepared from micro- to the impermeable protective clothing. Then, the effects of wearing time on the chest temperature, the back temperature, the hand and leg temperatures, and the rectal temperature of the volunteer wearers of the protective clothing with and without the cooling vest were measured at a room temperature of 36 ℃ and with a relative humidity of 60%. Moreover, according to the empirical formula of heat production and dissipation in the human body and the Woodcock equation, the relationship between the average body temperature and the wearing time was investigated. The results show that the cooling vest greatly reduces the temperatures of such body parts as the chest, the back, the hand, the leg and the rectal, and that the modeling calculation results of the variations in the average body temperature with the wearing time accord well with the experimental ones.