The invention relates to a drainage type pulse jet dust cleaning method with velocity difference jet, which comprises the following steps: an injection pipe b and an injection pipe a connected with a central jet pipe on the central axis of a jetting short pipe are controlled by the same pulse valve, and jet the compressed air at the same time; central jet and peripheral torus small hole jet form the velocity difference jet due to different velocities; the velocity difference jet enters a drainage pipe, and drains the clean air in a clean room in the meanwhile; a certain distance is kept between the lower end of the drainage pipe and the port of a filter bag, herein the velocity difference jet again drains mass clean air in the clean room and jets the clean air into the filter bag through the port of the filter bag; and the velocity difference jet is effectively sprayed at every part of the filter bag after entering the filter bag, and the peripheral torus small hole jet can effectively induce the central jet so as to lengthen the central jet and effectively clean the dust. The invention has no need of Venturi tube, so the dust on filtering materials with the height close to 200mm to 400mm of the filter bag port can also be effectively cleaned.