The ventilation system distribution valve is installed at the waist on the right side of the protective clothing; The purpose is twofold: (1) When the distribution valve of the ventilation system is connected to the air breathing apparatus and the internal ventilation and dehumidification system of the protective clothing, it has a cooling effect on the body; (2) When the chemical protective clothing is connected to an external air supply source, additional breathing air and ventilation and dehumidifying air can be provided from the external air supply source to extend the working time of emergency rescue personnel.