Abstract: The hybrid cascaded ultra-high voltage direct current (UHVDC) system of line-commutated converter (LCC) and modular multilevel converter (MMC) in series at receiving end provides a more economical, flexible and fast transmission mode for UHVDC transmission. Based on the existing coordinated control strategy of DC power grid, the coordinated control strategy among MMC valve groups is analyzed and studied, and five coordinated control strategies are considered. Then, with PSCAD/EMTDC, the response characteristics of the above five strategies subjected to different faults are simulated respectively, including sending-end AC fault, DC line fault, receiving-end LCC AC fault, receiving-end MMC1 AC fault and MMC1 immediately shutdown and exit. Finally, based on the simulation results, the applicability of the above five coordinated control strategies is compared and analyzed. The simulation results show that strategy 1 and strategy 3 ride through effectively under various faults. Strategies 2, 4, and 5 suffer from different degrees of power reversal under DC line fault, and the measures should be taken to restrain the power reversal.