The invention provides a buffering device for a power head of a down-hole drill. The buffering device comprises a thread connector, a spline shaft and a spline sleeve; the spline shaft is mounted in the spline sleeve; the spline shaft is mounted on the thread connector through the spline sleeve; the thread connector is connected with a power head main shaft; a circle of groove is machined on the outer side of one end at which the power head main shaft and the thread connector are connected; the upper end face of the thread connector is connected with the power head main shaft through a flange; the flange is formed by splicing at least two halves; a convex ring matched with the groove is arranged at the upper end of the flange; and after the flange is connected with the thread connector, the convex ring is mounted in the groove. The device not only has vibration absorption, buffering and thread protection effects, but also has certain guide effect; and the device and the power head main shaft have an anti-loosening function so that the utilization effect of the power head can be improved and the service life of the power head can be prolonged.