The utility model discloses a reinforced concrete air supply plenum chamber which comprises a chamber body composed of vertical plates, horizontal plates and step-type plates connected with the vertical plates and the horizontal plates. An air duct is defined by the vertical plates, the horizontal plates and the step-type plates, a vortex air supply port is formed in an upright plate of the step-type plate of each layer, and the vortex air supply ports are communicated with the air duct. By means of the reinforced concrete air supply plenum chamber, space of the structure is greatly used, and the reinforced concrete air supply plenum chamber is a necessary accessory for reducing dynamic pressure of an air supply system, increasing static pressure, stabilizing air flow and reducing air flow vibration. A cast-in-place reinforced concrete air supply plenum chamber technology reduces the area of a metal air duct by about 30%, and mechanical and electrical installation engineering cost is greatly reduced. Design and installation of a silencing system are omitted. In the technology, the plenum chamber and a body are constructed together, so that the procedure that the plenum chamber is constructed independently is omitted, the construction period is shortened, the air supply effect is more ideal, and the effects of energy conservation and environment protection are remarkable.