The conventional parameters calculation of grounding grid can only obtain the value of grounding parameters, but can not directly reflect step voltage, contact voltage and surface potential distribution. A new calculation method for grounding grid parameters was proposed according to the current field theory, in which the grounding grid was mathematical modeled by boundary element method, the grounding resistance was calculated by Matlab in vertical two layer medium demarcation, and the step voltage, the contact voltage and the surface potential distribution were imaged by Matlab graphical function. The result shows that this calculation method is precision and can be applied in the investigation of grounding grid parameters, which provides a technical reference for engineering application.