The working principle of the cordless drill is that when the cordless drill is rotating drilling, it is the same as the electric drill. The motor drives the gear transmission, the gear drives the connecting rod, and the drill bit rotates and cuts. When the impact mode is converted, the gear is in the inner shaft The upward jump drives the compressor piston in the impact piston tank to move back, and the compressive gas promotes the impact piston croot hammer head at the end of the drill head with a high impact force to impact the drill head forward.