A combined rocker arm apparatus for actuating auxiliary valve of engine, comprises an auxiliary actuator, a main rocker arm and a secondary rocker arm. The auxiliary actuator comprises an auxiliary rocker arm and an auxiliary cam. The auxiliary rocker arm and the main rocker arm are mounted on the rocker arm shaft in parallel. The auxiliary rocker arm is connected to the auxiliary cam at one end and adjacent to the secondary rocker arm at the other end. The auxiliary rocker arm includes a drive mechanism which provided with a piston. In the non-operation mode of the drive mechanism, the piston is drawn back, then the auxiliary rocker arm is disconnected with the secondary rocker arm; in the operation mode of the drive mechanism, the piston is pushed out, then the auxiliary rocker arm is connected with the secondary rocker arm.