The reasonable determination of preventive maintenance cycle and replacement cycle of train control center can improve equipment reliability and railway operation safety. On the basis of introducing recursion back factor and considering maintenance cost, a preventive maintenance cycle model of train control center based on time-varying reliability was established. The preventive maintenance cycle and replacement cycle of the certain railway train control center equipment was introduced as a simulation example. The calculation formula of equipment preventive maintenance cycle and maintenance cost was given with the constraint of time-varying reliability. With reliability benefit as the optimization goal, the best preventive maintenance times were determined. With maintenance cost as the optimization goal, the best preventive maintenance cycle and replacement cycle were provided. The research shows that the best preventive maintenance times of train control center equipment is 14 times and the best replacement cycle is 2.4 years. The model could effectively ensure the equipment highly reliable operation, arrange maintenance plans reasonably, Reduce maintenance costs to achieve profitability, and provide technical support for formulating the best repair policy.