Abstract: The multiple solutions of inversion cause some difficulties in geophysical prospecting data processing and interpretation. However, the equivalent source method just uses the multiplicity of solution through inversing the density of equivalent sources to obtain the real field underground. By using the prism as equivalent source, we calculated and analyzed the inversion imaging for the gravitational anomaly of theoretical 3D model, used the real gravity data to conduct calculation and processing. Good results were demonstrated theoretically and pratically, showing the viability and correctness of the method.