Surface soil radon could reflect deep underground hydrology, geology, mineral resources, heat source and other information, but the soil radon concentration has diurnal and annual variation characteristics. In order to study this problem, the authors used α spectroscopic cumulative radon instrument for continuous measurement. The results show that the law of soil radon concentration diurnal variation is of the single-peak type, the maximum value appears at the time interval of 19:00-22:00, with the minimum value at 11:00-14:00. Soil temperature is the key factor affecting the soil radon concentration, which is positively correlated with soil temperature. Rainfall has significant effects on soil radon concentration, which assumes double peak type after rain. The changes are related to meteorological factors such as soil humidity and air temperature.