Rotor-bearing systems play a vital role in machine tools, aero engines, and wind turbines. Generally, worn-induced degradation quantities and manufacturing errors of components are the main error sources that influence the precision reliability of rotor-bearing systems. The current precision reliability evaluation models are focusing on several error sources in only a few key components without agreeable results. Therefore, a precision reliability evaluation model is proposed considering all time-variant error sources and random error sources. Firstly, time-variant wear models for commonly occurred degradation types in a rotor-bearing system are developed. Secondly, the constructed time-variant wear models are inserted into the precision model with all moving components in the rotor-bearing system using the Meta-Action structural decomposition method. Finally, the time-variant stochastic process discretization method is employed to establish the precision reliability evaluation model, and solve the precision reliability of the rotor-bearing systems. Case investigations are carried out to verify the performance of the present model, which provides a better precision reliability evaluation model to estimate the conditions of rotor-bearing systems during the service period.