Since catenary is an associated system consisting of many components, the influence and difference between components should be taken into account in catenary maintenance. In this study, opportunistic mainte- nance model of catenary was established by interval mathematics, and it was transformed into a maintenance de- cision-making optimization problem based on reliability sensitivity. The objective of optimization was to minimize maintenance cost, and the constraints of reliability sensitivity of components and reliability index of catenary op- eration were taken as constraints. The optimal solution algorithm was used to optimize the opportunistic mainte- nance intervals of different components of the catenary. The results show that the optimization model of catenary maintenance based on interval mathematical method can effectively reduce the maintenance cost of catenary and provide guidance for catenary operation and maintenance on the basis of ensuring the reliability of the catenary system.