Double-wall spindle power head for core drill

The invention relates to a double-wall spindle power head for a core drill. The power head comprises an outer box body, a power mechanism, a transmission system, a spindle and a sealing unit, wherein the outer box body consists of a box body assembly and an upper box cover which are positioned by a positioning pin and connected by a screw; the power mechanism is a hydraulic motor or a motor; the transmission system consists of a driving gear shaft and a driven gear; the double-wall spindle consists of a spindle outer tube and a spindle inner tube; the spindle outer tube is connected with the driven gear through a spline; the driving gear shaft and the spindle outer tube, and the box body assembly and the upper box cover are connected through a rolling bearing respectively; a shaft hole and a key groove are reserved on the driving gear shaft and used for connecting the power mechanism; the spindle outer tube is provided with a through hole for washing solution to pass through; a sampler can be stored in a cavity of the spindle inner tube; and the sealing unit comprises a dynamic seal and a static seal. The power head has a compact structure and high sealing property, provides rotary motion, rotary torque and washing solution for the drilling of the drill, and is suitable for underwater and land core drilling; and an orifice is not required to be avoided and a water tap is not required to be disassembled when a core is taken.