Method for electromagnetic field problem of magnetoacoustic tomography with magnetic induction (MAT-MI) is presented, in which the static magnetic field need not rotating, and the transient electromagnetic effect which produced by the time-varying excitation can be taken into account. Beside, the huge computational effort for 3D cases can be reduced effectively. Program which based on the method was developed and applied. Through a number of calculating, the scope of application of the method has been researched, and the availability and efficiency of the method has also been demonstrated.