The utility model discloses a rocker arm chamber cover assembly device with a respirator. The structure is as follows: a rocker arm cover body is provided with a respirator working cavity which is internally provided with a maze type space. A cover plate for the respirator working cavity is tightly fixed on the rocker arm cover body for sealing by a sealing surface of the respirator working cavity with a bolt, so that the independent and closed respirator is formed in the rocker arm chamber cover body. The rocker arm chamber cover body is provided with a respirator air outlet, and is used for communicating a crankcase with air. A rocker arm chamber cover assembly is installed on an engine by the bolt on the rocker arm chamber cover body together with the respirator. In the utility model, the designed structure is simple and reasonable, and the peripheral space of the engine is effectively saved. The rocker arm chamber cover assembly with the respirator has following double functions: the rocker arm chamber cover seals the rocker arm working cavity, and also the separation of engine oil and gas, and the communication between the crankcase and air can be realized. The rocker arm chamber cover assembly device is conductive to the design of other engine accessories.