Abstract: Under the background of condition-based maintenance, there exist two kinds of failure（sudden failure and deterioration failure） for power equipment. To investigate the impact of failure dependence on equipment maintenance decision, this paper considered the handling of sudden failure and built up opportunistic maintenance decision-making model for power equipment. In consideration of the equipment failure rules, this model constructed equipment state transition diagram by Markov process. Furthermore, analytical expression of equipment risk and system operation risk were deduced based on opportunistic maintenance strategy. Finally, the equipment opportunistic maintenance decision-making model was built up to minimize the sum of equipment risk and system operation risk. Genetic algorithm was used to solve this model. The efficiency of this model is demonstrated by some practical examples. This model provides necessary foundation for optimizing equipment maintenance strategies.