Abstract: In order to satisfy construction demand of drilling in coal bed methane hole, cable hole and rescue hole, the multifunctional power head used in coal bed methane truck-mounted rig is developed. The power head which uses two displacement hydraulic motor to drive the gearbox has high transmission efficiency, large spindle path and wide regulation range. Spindle braking is developed to meet the directional drilling. The multifunctional power head can also be use in many different drilling technologies such as air hammer drilling and air-lift reverse circulation drilling. The field tests show that the multifunctional power head has high ability and efficiency, complete function, simple operation, and provides equipment guarantee for efficiently safe drilling construction.