Due to the hostile subsea environments, it is challenging to conduct efficient maintenance activities for the complex systems with failure dependences, especially when try to keep the maintenance activities sustainably simultaneously. Currently, there is no standardized method to assess the coupling impact of failure dependences and the effectiveness of maintenance on the overall sustainability. This chapter introduces an innovative, integrated framework that uses Bayesian networks to comprehensively analyze the combined effects of component degradation, failure dependences, and maintenance management on the sustainability of these complex subsea systems. The proposed model explores the impact of various maintenance strategies and failure dependences on overall sustainability. A case study demonstrates the importance of considering failure dependences and the practicality of the sustainability evaluation model, offering solutions for optimizing maintenance strategies from a sustainable perspective. The research contributes to improving the maintenance and reliability of complex subsea systems at reasonable costs, providing valuable guidance for decision-makers seeking sustainable maintenance practices.