Macromolecular medical catheter fitting and connecting method thereof

The invention relates to the field of medical accessories, in particular to a macromolecular medical catheter and pipe fitting connecting method which comprises the following steps that 1, an etching pipe penetrates through a first pipe and is inserted into a second pipe, and the etching pipe is located at the joint of the first pipe and the second pipe; 2, a high-temperature-resistant air bag is introduced into a pipe cavity of the etching pipe, and the high-temperature-resistant air bag moves to the joint of the first pipe and the second pipe; 3, heating treatment is conducted on the joint, in the process, the high-temperature-resistant air bag is filled with fluid so that the high-temperature-resistant air bag can expand to open the pipe cavity of the etching pipe, and under the expansion effect of the high-temperature-resistant air bag, the outer wall of the etching pipe can be attached to the inner walls of the first pipe and the second pipe of the outer cavity pipe; and 4, the fluid in the high-temperat