The invention discloses a full-seam mining coal mining machine and a coal mining method, and belongs to the technical field of coal mining. The full-seam mining coal mining machine comprises a main machine frame, an upper cutting device, a lower cutting device and a turning device, the upper cutting device and the lower cutting device are mounted on the main machine frame, the upper cutting deviceis connected with the main machine frame through the turning device, the turning device comprises a power mechanism, a rotating arm is arranged at the output end of the power mechanism, when the coalmining machine cuts coals to the end, the power mechanism acts to drive the rotating arm to rotate, and then, the upper cutting device is driven to rotate together; and the upper cutting device comprises a cutting head, a cutting arm, a telescopic cylinder, angle modulation oil cylinders and a rotating part, the rotating part is connected with the rotating arm, the cutting head is tapered, the rear end of the cutting head is connected with the cutting arm, and the rear end of the cutting arm is connected with the telescopic cylinder. According to the full-seam mining coal mining machine and the coal mining method, turning and moving of a cutting part can be realized by using the turning device, cutter-entering coal cutting can be continuously carried out during returning, cutter-empty return is avoided, reciprocating and bidirectional coal cutting can be realized, the working efficiency is improved, and energy consumption can be reduced.