Abstract: To achieve the collection and long-distance transmission of large-scale onshore renewable energy sources such as wind power, this paper proposed a hybrid cascaded DC transmission system suitable for the hierarchical access of multiple wind power bases with different scales. Firstly, the topology and operating characteristics of the hierarchical access-hybrid cascade transmission system were introduced. The system was designed with a double-layer structure, which could realize the access of wind farms of different scales. The high-voltage valve adopted the line commutated converter, and modular multilevel converters were connected in parallel as the low-voltage valves. Then, the mathematical model of the system was built, and the coordinated control strategy was designed accordingly. To respond to the wind farm output fluctuations, the adaptive P-V droop control was designed to ensure the stable operation of the system. Finally, a simulation model of the hierarchical access-hybrid cascade transmission system was built in PSCAD/EMTDC to verify the effectiveness of control strategies. The research results show that the system could be an alternative for long-distance transmission of large-scale wind power.