Abstract: In order to complete ship electric static field inversion work, a method is proposed based on the point charge source. Firstly, the number and accurate location of equivalent source is calculated by using the Taylor expansion radius of convergence, and then, the linear equations in three layer model of air-seawater-seabed for calculating the equivalent point source and the vessel equivalent electric moment is established. Finally, the effectiveness of the method is verified by the Beasy simulation data, the results show that the algorithm is with high precision.