Quantitative injection device for injection

The utility model relates to the technical field of injection devices, and discloses a quantitative injection device for injection, which comprises an injection cylinder, scale marks are arranged on the outer surface of the injection cylinder, a needle head is fixedly mounted at the bottom end of the injection cylinder, the needle head is communicated with the inside of the injection cylinder, and a piston is mounted on the inner wall of the injection cylinder in a sliding manner. The sliding sleeve is driven by the driving assembly to slide along the outer surface of the syringe, the cover plate is driven by the sliding sleeve to move to a designated position, so that the required injection amount is adjusted, the push rod drives the piston to move along the syringe by pulling the pressing pad, negative pressure is formed in the syringe, and injection liquid is sucked into the syringe. When the baffle on the push rod moves to the position of the cover plate, the piston moves to the designated position throug