The invention discloses an operating room air purification device and a mounting method thereof. The device comprises a body, wherein the body is provided with an air outlet pipe and air suction pipes, the air outlet pipe is arranged at the top of an operating room, an air outlet penetrates through the top in the operating room, a front end of the air outlet pipe is connected with the air outlet,air suction openings are formed at bottoms of two sides in the operating room, front end of the air suction pipes are connected with the air suction openings, a tail end of the air outlet pipe and tail ends of the air suction pipes are tightly attached to a rear side wall outside the operating room, a circulating air inlet assembly communicates between the tail ends of the air suction pipes, and apurifying assembly is connected between the tail end of the air outlet pipe and the top of the circulating air inlet assembly. The method comprises steps of a, preparation before installation, b, mounting of the air outlet and an air suction port, c, mounting of the air outlet pipe, and d, mounting of the purifying assembly, the air suction pipes and the circulating air inlet assembly. The devicereduces or eliminates dust, microorganisms and bacteria in the air in the operating room, avoids influence on a patient in the operation process, and improves the success rate of an operation.