The utility model discloses an apparatus for grounding grid corrosion diagnosis. The apparatus for the grounding grid corrosion diagnosis comprises a potential pole, a backflow pole and a current injection pole distributed in a grounding grid. The backflow pole and the current injection pole are connected through an excitation source. The potential pole is connected with a potential control pin through a digital oscilloscope. The potential control pin is used for measuring potential values. The excitation source comprises a signal generation portion. An output of the signal generation portion is divided into two paths. One path is connected with a frequency display circuit, and the other path is connected with a power amplification portion. An input of the power amplification portion is connected with an impedance converter. An output of the impedance converter is divided into two paths. One path is connected with a grounding grid load, and the other path is connected with an output current display circuit. The signal generation portion and the power amplification portion are supplied with electric power by a power supplying power source. According to the utility model, digging of a grounding grid in a large area is not needed; manpower and material resources waste are significantly avoided; restrictions by on-site operation conditions do not exist; normal operation of an electric power system is guaranteed; and the apparatus for the grounding grid corrosion diagnosis has a wide application prospect and a market value.