Abstract: With the development of high voltage direct current（HVDC） transmission, flexible DC and conventional DC are connected to the same bus or relatively close AC bus to form a hybrid multi-feed AC/DC system. In order to take full advantage of the characteristics of flexible DC power decoupling and rapid adjustment, reduce the probability of conventional DC commutation failure, and maintain the safety and stability of voltage for the hybrid AC/DC system, a hierarchical coordinated medium-and longterm voltage control method in the hybrid multi-infeed AC/DC system is proposed. Firstly, the hybrid multi-feed AC/DC system is modeled, and the solving method of the sensitivity of the control variable to the AC bus voltage in different flexible DC control modes is analyzed. Secondly, a two-level coordinated voltage control is constructed. The system-level control aims at the lowest node voltage trajectory deviation of the AC system and the minimum control cost. The station-level converter control aims at ensuring the conventional DC infeed bus voltage and commutation margin. Different control schemes are designed according to the reactive power margin of the generator, and the two-level coordination strategy is designed for control of the arc extinguishing angle and active power of conventional HVDC transmission to avoid control conflicts. Finally, the simulation results show that the proposed control method can significantly improve the medium-and long-term voltage stability of the hybrid AC/DC system.