Abstract: According to the features of combined plasma arc and the theory of magnetic fluid dynamics and electromagnetics, which exists a coexistence of transferred arc and non-transferred arc and an interaction of electric field, magnetic field, thermal field and flow field, a three-dimensional mathematical model was developed. The effects of working current and gas flow on the distribution of jet temperature of the combined plasma arc were analyzed by finite element software ANSYS and sequential coupling method. The results show that the simulation value with this model is consistent with the measured value.