The invention relates to a protective mask with a drainage valve, and belongs to the field of labor insurance protective equipment. The protective mask is composed of an outer cover plate, a mask body, a filter, an inhalation valve, an exhalation valve and the drainage valve. The inhalation valve is installed in the front of the mask body. The filter is installed in front of the inhalation valve. The outer cover plate is installed in front of the filter. The inhalation valve is installed at the lower portion of the mask body. The drainage valve is installed at the bottom of the mask body. The drainage valve is composed of a drainage valve body and a drainage valve element. The drainage valve is installed at the lowest position of the protective mask in the working state; when water is gathered inside the protective mask, water can be directly drained out of the mask through exhalation; during inhalation, the drainage valve can be rapidly turned off through air flow flowing through a gap of a drainage valve plate. The problems that when an existing protective mask is used at low temperature and particularly used in a cold place, condensate water inside the mask will affect the valve plate of a respirator inside the mask and particularly affect turning-on and turning-off of the exhalation valve, the sealing performance is poor, leakage is caused, and the gas defense effect of the protective mask is affected are solved.