The invention discloses a geological exploration multi-process drilling machine power head. The geological exploration multi-process drilling machine power head comprises a box, and the middle of the box is vertically provided with a power head output shaft; a plunger variable motor and a low-speed motor are arranged on the box and matched with the power head output shaft through a transmission system; the upper end of the power head output shaft is provided with a hydraulic chuck which is matched with a drill stem; the output shaft of the low-speed motor is provided with a gear shifting mechanism; a lubricating and cooling system is arranged outside the box. The geological exploration multi-process drilling machine power head also comprises a hydraulic control system. The geological exploration multi-process drilling machine power head can achieve rapid switching between high-speed small torque and low-speed large torque, meet the requirements of a diamond rotating cable core drilling process and an air reverse circulation rapid sampling drilling process, select different drilling processes according to different stratum conditions and different drilling depths, conveniently perform switching to achieve multiple purposes, reduce the cost and improve the exploration efficiency.