The two-terminal hybrid HVDC transmission technology with line commuted converter on the rectifier side and modular multilevel converter on the inverter side can reduce the risk of commutation failure and possesses the advantages of low cost and small loss meanwhile, which has a broad application prospect. In HVDC transmission system, single-pole to ground fault of transmission line is one of the most common fault types. Single-pole to ground fault analysis is of vital importance. This paper introduces an analytical method of fault characteristics of two-terminal hybrid DC transmission system in the case of single-pole to ground fault. It aims at the fault detection stage when electromagnetic transient stress changes sharply, uses the differential and common mode transformation methods to solve coupling problem of transmission line, the asymmetry problem of DC fault and other nonlinear problems, establishes the model of each part of the system, and finally gives an analytical result of the system fault characteristics. Simulation verification is carried out in PSCAD/EMTDC, and the coincidence between analytical results and simulation results is more than 95%.