In order to understand the gas-solid insulation system under DC voltage, a simulation model is developed to determine the electric field distribution in such systems. Various influencing factors are integrated in the simulation model, including the temperature and field-dependent volume und surface conductivity, the shape of the insulator, the polarisation and the dark current. The effects of the influencing factors are investigated individually. The combination of the influencing factors that results in the highest field strength in the gas-solid insulation systems is determined, which gives a worst-case scenario.