Axial fixing structure of gas turbine combination bearing and disassembly and assembly method

The invention discloses an axial fixing structure of a gas turbine combination bearing and a dismounting and mounting method. The axial fixing structure comprises a gas compressor shaft, the front end portion of the gas compressor shaft is sleeved with a combination bearing, the front end portion of the gas compressor shaft is further connected with a detachable fixing sleeve, and the fixing sleeve is arranged on the front side of the combination bearing and axially limits the combination bearing. A bearing box used for fixing the fixing sleeve and the combination bearing together is further arranged on the outer side of the fixing sleeve and the outer side of the combination bearing. The dismounting and mounting method comprises the following steps: step 1, dismounting the fixed sleeve; 2, a rotor temporary support is installed at the front end of the gas compressor shaft; 3, a bearing temporary support is arranged below the rotor temporary support; 4, the combined bearing is axially moved out; and 5, the co