The invention discloses a method for predicating the corrosion rate of soil of a transformer substation grounding grid. A current parameter analyzing method cannot well solve the grounding grid corrosion rate predicating problem. The method includes the steps that sampling points are reasonably distributed in a selected area; soil parameters are measured at the sampling points, the soil parameters comprise the resistivity, the moisture content, the redox potential, the pH value and the volume weight, a soil sample is collected back to a laboratory to conduct the measurement of salinity and the chloride ion physical and chemical property, and meanwhile an electrochemical method is used for measuring the corrosion rate of metal materials in the soil; the seven indexes of the resistivity, the moisture content, the redox potential, the pH value, the volume weight, the salinity and the chloride ion are used for setting up a model, and a BP neural network is used for training measured data. The method is fast, effective, accurate in predication and capable of providing a reliable basis for predicating the corrosion rate of the soil of the transformer substation grounding grid.