Abstract: In order to evaluate the reliability of the VSC-HVDC system,its structure and subsystems are introduced.Based on the state space method and k-out-of-n（G） model,the reliability models of components,subsystems and whole system of VSC-HVDC system and indices algorithms are proposed.The proposed models can completely reflect the impact of spare components on system reliability.In the end,the models and relative methods are simulated by Matlab,and results show that cold standby components can improve the system energy availability significantly,while hot ones can reduce failure rate of the system.