Cement mixing pile grouting hole device capable of automatically opening and closing

The invention discloses a cement mixing pile grouting hole device capable of automatically opening and closing, and relates to the field of cement mixing piles of building foundation treatment. When the cement mixing pile works, spraying is needed in the pre-mixing sinking and the again-mixing process, otherwise, a spraying hole is prone to being blocked, and more cement is wasted. Cement mixing pile grouting hole device comprises a steel pipe section provided with a spraying hole, the upper end of the steel pipe section is connected with a power drilling pipe through a threaded screw, the lower end of the steel pipe section is connected with a drill bit point through a threaded screw, the steel pipe section is internally provided with a piston, a spring and a support bracket, the support bracket is fixed to the drill bit point, the spring is connected with the piston and the support bracket, before drilling, the spraying hole on the side wall of the steel pipe section is blocked by the side wall of the pisto