The invention discloses a dynamic simulation system of an offshore wind power power-transmission and grid-connected system through a VSC-MTDC. A main circuit frame of a grid-connected system is given, a design scheme of a monitoring system is improved, a monitoring system framework based on a central monitoring system and convertor station monitoring system double-layer structure is provided, an interface scheme of a fan simulation device monitoring system and a convertor station monitoring system is given, and a coordination control method between VSC-MTDC power transmission system network side converter stations is designed. The dynamic simulation system is advantageous in that a reliable and convenient research platform is provided for a system scheme of the offshore wind power power-transmission and grid-connected system through the VSC-MTDC, control system design, control strategy research and dynamic response characteristic analyses, and a good test environment is provided for system engineering development and debugging.