Screw drilling tool

The utility model discloses a screw drilling tool. A bit pressure control valve is assembled between a bypass valve assembly and a motor assembly and comprises a valve body and a valve element, wherein the valve body is connected to a stator of the motor assembly, and the valve element is connected to a shell of a bypass valve. An ejecting head is arranged at the front end of the valve element, a hydraulic channel is formed in the valve element, and a fluid distribution opening is formed in the circumferential wall of the valve element. The front end of the valve element is sleeved with a resetting spring. In the using process, when the discharge capacity of drilling fluid reaches a certain value, hydraulic pressure of the drilling fluid will force a bypass port of the bypass valve assembly to be closed, and at the moment, the drilling fluid will flow into a hollow channel inside a rotor of the motor assembly through the hydraulic channel in the valve element of the bit pressure control valve when the sand surface in a well is soft so that the drilling fluid can be jetted out from a water hole of a drill bit to flush out sand columns inside the well. In this way, when the sand surface is soft, hydraulic drilling can be achieved through control over the bit pressure control valve.