Abstract: On the basis of analyzing load characteristics of full hydraulic truck-mounted rotary system, a hydraulic control system with two-pump and two-circuit control was designed. The system achieves constant torque through remote relief valves which can protect the screw of drilling tool. An oil feeding circuit is designed. When the rotor is impacted, the oil will be added to the positive and reverse drive oil circuit to avoid the phenomenon of suction. A coalbed methane well with the drilling length of 1 358 meters in Jincheng Sihe Coal Mine was successfully drilled by ZMK5530TZJ60 type truck-mounted drilling rig, which validated the rationality and reliability of the designed feeding circuit.