Positive displacement motor drill and rock breaking well drilling method thereof

The invention relates to a positive displacement motor drill comprising an anti-falling assembly, a motor assembly, a universal drive shaft assembly, and a transmission shaft assembly. The transmission shaft assembly consists of a mandrel, a lower TC outer cylinder, an upper gear, a transmission rod, a lower gear, a valve shell, a moving valve block, and a fixed valve block; the moving valve block connected with the lower gear of the transmission shaft assembly by an outer gear ring is arranged inside the mandrel of the transmission shaft assembly; the mandrel and the valve shell are in threaded connection; the fixed valve block is fixed inside the valve shell by threads; and the rotatable moving valve block and the fixed valve block fixed inside the valve shell are in contact by a smooth end surface. In addition, the invention also relates to a rock breaking well drilling method of the positive displacement motor drill. On the basis of the positive displacement motor drill and the rock breaking well drilling method thereof, the rock breaking efficiency and the mechanical well drilling speed can be effectively improved; and the well drilling cost is lowered.