分析了高压直流输电系统(HVDC)的基本结构及原理，在MATLAB/Simulink中建立基于6脉冲桥的高压直流输电系统的仿真模型。分别对系统的稳态和暂态过程进行仿真分析，主要对系统发生直流线路接地短路故障时进行仿真分析，仿真结果验证了HVDC模型系统的正确性及合理性，能够更加准确的观测到HVDC系统的动态性能。 The basic structure and principle of HVDC power transmission system are analyzed. A simulation model for 6-pulse bridge HVDC power transmission system is built in MATLAB/Simulink. The steady and transient processes of this system were simulated especailly when DC line grounding fault occurs. The simulation results verify the accuracy and rationality of the HVDC model system. The dynamic performance of this HVDC model system can be observed more accurately.