Under the action of instantaneous short-circuit impulse current, the cable core will lead to short-term heat accumulation, which will cause the breakdown of the cable insulator and cause fire, and even cause explosion. Therefore, it is a key factor for cable fire warning and risk assessment to accurately obtain the temperature change of the inner conductor of the cable. This paper proposes a multi-medium fusion temperature field calculation model of 10kV cable conductor. Compared with the current common thermal circuit model and finite element simulation numerical calculation model, the temperature field calculation and simulation model proposed in this paper comprehensively considers the influence of multiple media such as load current, external environment, excessive short-term load and protective layer grounding current on the cable conductor temperature field. It has the advantages of wider constraint conditions and closer to the actual environment application. The effectiveness and reliability of the proposed model are verified by the experimental results of the given simulation model.