The invention discloses a multidisciplinary, long-periodic and reliable modeling method of a hydraulic servo mechanism based on a failure mechanism. The method is implemented by five stages: firstly, carrying out system modeling, namely carrying out dynamics mechanism modeling, dynamics mechanism parameterization and hydraulic system modeling; secondly, carrying out joint simulation, namely setting a joint simulation environment, building a joint simulation platform, selecting a joint simulation mode, setting a transfer function, and operating joint simulation; thirdly, injecting individual discipline failure mechanism and mode, namely injecting a failure mechanism of a dynamics mechanism and a hydraulic system failure mode; fourthly, injecting multidisciplinary failure mechanism and mode, thus injecting failure mechanism and modes into a hydraulic system and the dynamics mechanism; and fifthly, carrying out simulation analysis, analyzing single failure influence, finding out weak links and key parameters of a system, and depicting the degradation paths and performance degradation paths of the key parameters, thus obtaining reliable related data. According to the method, the multidisciplinary failure mechanism and mode injection is realized for the first time, and the long-periodic and reliable modeling method is perfected.