The invention discloses a mounting method of protection leather hoses of a transmission shaft sliding fork protection frame. The mounting method is carried out by the following steps of: I. communicating one end of a protection leather hose with a high-pressure gas source; II. sheathing the free end of the protection leather hose on the free end of a protection steel pipe of the protection frame, and opening an air valve to ensure that high-pressure gas flows from the high-pressure gas source and then flows out from the free end of the protection leather hose after flowing through a circular cylindrical space between the protection leather hose and the protection steel pipe; III. enabling the protection leather hose to advance along the protection steel pipe until the free end of the protection leather hose arrives at the tail end of the protection steel pipe; IV. shearing off the protection leather hose at the free end of the protection steel pipe; and V. repeating the steps II to IV in allusion to the protection steel pipe of a next protection leather hose to be mounted until the protection leather hoses are arranged on all the protection steel pipes on the protection frame. According to the mounting method and device, the work efficiency is improved, the labor intensity of operators is reduced, effective protection functions are provided and the service life of the protection leather hose is longer than that in the prior art.