An irregular mesh mapping method used in electromagnetic field-flow field-temperature field coupling calculation comprises the following steps of 1 establishing a flow field-temperature field calculation model; 2 reading node coordinate values of discrete units of the model; 3 re-establishing a geometric model of a research object in the electromagnetic field calculation, performing model discrete to form a triangular finite element mesh and performing electromagnetic field value calculation; 4 mapping power consumption onto units in a temperature field; 5 obtaining a mapping correction factor; using power consumption densities of the units as loads to be loaded into the temperature field for solution and calculation, and obtaining a temperature result; accordingly obtaining the power consumptions of the units in the temperature field. By adopting the irregular mesh mapping method used in the electromagnetic field-flow field-temperature field coupling calculation, data transfer of different types of meshes can be adopted in different physical fields, the mesh number is greatly decreased, and the calculation time and the calculation accuracy are shortened and improved.