The invention discloses a water spraying device for milling based on a precision numerical control machine tool. The water spraying device comprises a machine tool spindle. The bottom end of the machine tool spindle is fixedly connected with a tool rest; a damping mechanism is fixedly connected to the bottom end of the outer side of the machine tool spindle; and the damping mechanism comprises a fixing ring, a mounting groove, a limiting groove, a fixing groove, an offset block, a connecting block, a limiting block, a buffer spring, a connecting round block, a buffer rubber pad and a mountingbox. Through cooperation of a special-shaped ring, a sealing pipe, a sealing spring, a sliding rod and a special-shaped block, the size of an opening between the special-shaped ring and the special-shaped block is adjusted, so that flow velocity of cooling liquid in a spray housing keeps dynamic balance, the cooling liquid can be sprayed to a cooling position all the time, and the cooling effect is improved; and through cooperation of the annular groove, the control pipe, the spiral driving groove, the driving connecting rod and the connecting disc, the spraying flow speed of the cooling liquid is changed, and the using process of the water spraying mechanism is optimized.