The utility model provides an ash clearing device for a waste heat boiler, which comprises a boiler body (9). The top of the boiler body is uniformly provided with a plurality of air inlets (10) penetrating through a boiler cavity (3), a heat conducting coil pipe (5) is mounted on the outer periphery of the boiler body, a compressed air delivery pipe (8) is arranged above the boiler body, and an electromagnetic valve (7) and a control box (1) are sequentially arranged on the compressed air delivery pipe (8). An air inlet pipe (11) is connected to each air inlet, a pulse control valve (6) is mounted on each air inlet pipe, and the tail ends of the air inlet pipes (11) are connected together and communicated with the compressed air delivery pipe (8). Air shots formed by pulse compressed air and a vibrator are used for shaking off ash attached on the heat conducting coil pipe, heat exchange effect of the waste heat boiler is effectively improved, effective heat utilization rate is increased, and production and operation cost is reduced.