The key factor restricting the maneuverability of mobile radar is the system electrical grounding. By the theoretical research and actual verification of vertical grounding grid, horizontal grounding grid, and complex grounding grid, the approximate calculation method is proposed for electrical grounding resistance of different grounding grids. On the basis of theoretical derivation, the estimated algorithm for the mobile grounding network is proposed. The proposed algorithm is proved to be simple and feasible by the measurement results. The method has been applied to a certain type of mobile radar and provides important technical support for the fast deployment task of mobile radar.