Main bearing is one of the most important parts of TBM. The normal service of the main bearing has great influence on the improving of the TBM availability and the progress of the tunneling. In the paper, the failure types of the main bearing are presented, the maintaining of the main bearing and the countermeasures for the malfunctions of the main bearing of the TBM used in the construction of West Qinling tunnel on LanzhouChongqing railway are analyzed, and the key points in maintaining and application of the main bearing are summarized. The paper can provide reference for the operation, fault detection and service life improving of main bearings of other TBMs in the future. 