Hybrid DC converter is composed of a fully controlled auxiliary converter and the diode rectifier. Compared with the traditional modular multilevel converter（MMC）

the number of submodules is greatly decreased so as to increase the economic efficiency of the offshore DC transmission. However

the research on the precharge strategy of this converter is not available in literature presently. Therefore

the startup strategy of the hybrid DC converter is proposed in this paper. Firstly

the startup process of the hybrid converter is divided into two stages: uncontrollable stage and controllable stage. For the uncontrollable stage

the relationship of the capacitor voltage of the submodules is analyzed and the computation method of the current limiting resistance is proposed. For the controllable stage

two different precharge schemes are proposed. The first scheme based on parameter design is simple and effective. But the modularity of the topology is decreased and the application cost is increased. The second scheme based on circulating current control is more flexible without sacrificing the modularity of the topology. But the precharge process is more complicated and slower. Finally

the feasibility of the proposed startup strategy is verified through the simulation models of hybrid converter in MATLAB/Simulink environment.