With the aging of catenary components, maintenance faces growing challenges. Addressing the lack of theoretical support and over-reliance on empirical maintenance scheduling, this paper proposes a dual-objective optimization model for imperfect maintenance strategies. A hybrid failure rate model describes reliability under imperfect maintenance, while opportunistic maintenance is introduced to establish the cost function. The dual-objective model minimizes maintenance cost and maximizes reliability by optimizing opportunistic maintenance reliability thresholds. An Multi-Strategy Improved Dung Beetle Optimization algorithm incorporating Bernoulli mapping, improved sine strategy, nonlinear convergence factors, and Gaussian-Cauchy mutation is developed for solution. Case studies demonstrate the model and algorithm effectively formulate economical and reliable maintenance plans, significantly improving strategy flexibility and practicality.

Catenary system; Dung Beetle Optimization algorithm; Imperfect maintenance; Dual-objective optimization; Opportunistic maintenance