Abstract: The influence factors of field test of soil resistivity are complex, so it is necessary for geophysical prospecting technicians to operate skillfully and obtain reliable original data; At the same time, the interpretation of soil resistivity needs geophysical prospecting technicians to reject the disturbed and distorted data, and to use reasonable interpretation method to analyze and conclude the original data, so as to reproduce the mechanism of soil conductivity truly.Taking the grounding of a substation as an example, this paper analyzes and compares the two methods of the first-interpretation-then-average method and the first-equivalent-then-interpretation method, and obtains the most suitable interpretation method of soil resistivity in Shanghai.