Abstract: Transcranial magnetic-acoustical-electrical stimulation (TMAES) can modulate the firing activity of neurons in the corresponding regions of brain by electric field induced by the combined effect of ultrasound and static magnetic field, and the focusing performance of the induced electric field is a key factor in determining the regulation accuracy. In this paper, we explored the evaluation method of focusing degree of induced electric field by performing modeling, simulation analysis, selection of evaluation index and analysis of electric field focalization. We chose five indicators to measure the level of electric field focalization:depth and intensity of stimulation, focusing area, length of focal region and gradient coefficient of electric field intensity. The results showed that TMAES had good efficacy in stimulating the brain and possessed a high resolution. And the above indicators can accurately describe the distribution characteristics of the induced electric field, and the evaluation method we established can effectively evaluate the focusing performance of TMAES induced electric field.