Pre-filled catheter flusher capable of avoiding repeated utilization

The utility model relates to the technical field of medical instruments, and provides a pre-filled catheter flusher capable of avoiding reuse, which comprises a needle cylinder, a push rod, a piston and a protective cap, the piston is arranged in the needle cylinder, one end of the push rod is connected with the piston, the other end of the push rod extends out of the needle cylinder, and the protective cap is connected with an injection end of the needle cylinder; a clamping ring is fixedly arranged in the open end of the needle cylinder, a protruding ring is arranged on the outer circumferential face of the clamping ring, a first clamping groove is formed in the inner circumferential face of the open end of the needle cylinder, and the protruding ring is fixedly connected with the first clamping groove in a clamping mode. A through groove is formed in the inner circumferential surface of the clamping ring, and a second clamping groove is formed above the through groove; when the push rod moves towards the i