This paper is prepared based on the monitoring data of the Meteorological Bureau of Hechuan District, Chongqing for the whole year by the automatic monitoring system on soil resistivity and soil water content of the observation site. The influence of soil water content on water resistivity is analyzed, the correlation between the soil resistivity on monthly, daily and hourly basis and the water content researched and the regression model established between water content on daily and hourly basis and the corresponding soil water content for soils at different depths, which provides a reliable mathematical calculation approach for the estimation of soil resistivity at different depths for lightning hazard risk evaluation and lightning proof engineering design and solves the problem of lacking historical observation data on soil resistivity in practical operations.