Rotary locking device and method for rotary drilling rig

The invention discloses a rotary locking device and method for a rotary drilling rig, and belongs to the technical field of engineering machinery. The device comprises a rotary platform, a frame, a positioning device, a locking device and a detection device; the revolving platform is connected with the frame, the frame is rotatably mounted at the bottom of the revolving platform through a slewing bearing, the positioning device is fixedly mounted on the revolving platform, and the locking device is accommodated in the frame and matched with the positioning device; the locking device is in clearance fit with the positioning device through a positioning pin; the locking device comprises a locking block, an annular oblong hole, an oil duct, a plurality of ejector pin holes, a supporting ejector pin, an elastic piece, a supporting sealing piece and a plug. The locking device applies pressure to the elastic piece and the ejector pin through the pressure of hydraulic oil, then the ejector pin is driven to move in t