The distribution of the induced electric field generated intracranially by transcranial magneto-acoustic electrical stimulation is a key factor in determining the accuracy of neuromodulation. Phased arrays can generate highly focused acoustic fields, but the relationship between their structural parameters and intracranial induced electric fields is unclear. In this paper, a three-dimensional finite element model containing the phased array was developed, and the acoustic field distribution was calculated and evaluated by using the cross-sectional area of the focal zone, the depth of the focal zone, the acoustic intensity and the electric field strength. The actual electric field intensity at the focal area was measured by designing a mimic experiment. The effect of the phased array on the local field potential of rats at 0.8 MHz center frequency with different number of array elements coupled with 0.3 T static magnetic field was investigated using Wistar rats as the experimental object. The results showed that increasing the number of array elements could increase the electric field intensity in the focal area, and then decrease the oscillation frequency in the low frequency band (4-30Hz) and increase the energy in the high frequency band (30-80Hz), which revealed the mechanism of neuronal excitability regulation by phased array-based focused transcranial magnetoacoustic stimulation, and provided a reference for the design of transcranial magnetoacoustic stimulation system and the selection of phased array structure parameters.