Improved medium-length catheter

The improved medium-length catheter comprises a connecting port, a pre-connecting piece, a long catheter body, a supporting guide wire and a three-way valve, the connecting port is formed in one end of the pre-connecting piece, the other end of the pre-connecting piece is communicated with the long catheter body, and a contraction neck is arranged in the middle of the pre-connecting piece. The supporting guide wire is arranged in the pre-connecting piece and extends along the interior of the long catheter all the time, fixing lugs are arranged on the two sides of the pre-connecting piece, fixing belts are arranged on the two sides of each fixing lug, a first connecting buckle and a second connecting buckle which are matched with each other are arranged on the fixing belts on the two sides,and the tail end of the long catheter is arranged in a round and closed mode. And the three-way valve is arranged at the tail end of the catheter. The catheter can prevent catheter blockage and air embolism, reduces tube was