Silicone elastomer has high temperature resistance and good insulation performance, and is one of the packaging materials for SiC device packaging. The accumulation of space charge in polymer materials can lead to electric field distortion, which affects device reliability. In this paper, the space charge characteristics of silicone elastomer under different DC voltages are studied, which shows that the same polarity charge accumulation exists in silicone elastomer. Charge accumulation gradually reaches a stable state, and the charge distribution inside the medium also reaches a stable state. A one-dimensional simulation model is established. The space charge characteristics of silicone elastomer are studied by numerical simulation. By comparing with the experimental results, the validity of the simulation model and parameter setting is verified. The above model and parameters are directly applied to the calculation of space charge distribution under DBC structure. The electric field is larger and the charge accumulation phenomenon is more obvious at the triple junction points.