Downhole pressure wave generating device and method and application

The invention relates to the field of offshore oilfield oil extraction, in particular to an underground pressure wave generating device and method and application. The device comprises a device body, a center channel penetrating through the device body, a main channel communicating with the center channel in the device body and a signal transmission unit in the device body, and the center channel is provided with a switch used for controlling injection liquid to be directly injected into a well along the center channel or controlling the injection liquid to flow into the main channel from the center channel; the lower part of the main channel is provided with a pressure wave generating unit for receiving injection liquid from the main channel and further generating pressure waves; a control unit for controlling the switch is arranged at the upper part of the main channel; the signal transmission unit sends instructions to the control unit and the pressure wave generation unit through the control cable. By mea