The utility model relates to an exhaust gear for a speed reducer and belongs to the technical field of speed reducers. The exhaust gear for the speed reducer is simple and reasonable in structure, and capable of exhausting steam in the speed reducer, balancing pressure and preventing oil leakage. According to the technical scheme, an air outlet pipe is arranged on the upper portion of a speed reducer shell, an oil return pipe is arranged on the lower portion of the speed reducer shell, the air outlet pipe is communicated with an exhaust pipe, the exhaust pipe is vertically arranged, the bottom of the exhaust pipe is communicated with the oil return pipe, a filter screen is arranged in the exhaust pipe, the top of the exhaust pipe is provided with a hole cover, and a through hole is formed in the middle of the hole cover. The exhaust gear for the speed reducer is simple, convenient to use and capable of preventing oil leakage effectively, and is widely applied to exhaust and deflation of the speed reducer.