Based on the lumped parameter theory of piezoelectric transducer, the mathematical relationship between mutual radiation impedance and surface vibration velocity distribution of the array element is established, and then the simulation experiments were carried out for a 5×5 planar array. The simulation results show that the influence of amplitude and phase caused by mutual radiation impedance presents the features of oscillation curves in the condition of low frequency, small array element distance and large array element number. Mutual radiation impedance effect on surface vibration velocity distribution should be controlled in the large emission array design.