In view of the frequent explosion accidents of 110kV cable joints, the temperature field of cable joints with crimping defects was analyzed, and the degree of crimping defects was quantitatively characterized. COMSOL finite element software is used to establish the cable joint temperature field model. Through the analysis of simulation data, it is found that when there is extra contact resistance, the cable joint will produce abnormal temperature rise, but it has little influence on the temperature of the remote cable body. On this basis, the influence of ambient temperature and current load on core and skin temperature of cable joint under different working conditions is studied, which provides a data basis for subsequent characterization of crimping degree. Finally, the simulation data under different working conditions were fitted to obtain the representation equation of crimping coefficient based on the surface temperature difference method. The calculation method can calculate the cable core temperature quickly and accurately, and provide a basis for the temperature monitoring and state evaluation of the cable middle joint.