By the synthetically comparing observation of the gas Rn with the volumetric strain,air pressure,water level,water temperature and atmospheric temperature at Shunyi station in Beijing,it is found that in the curves of daily changes of gas radon from ground water there exists a tide phenomenon,and its value is closely related with the theory value of volumetric strain solid tide. To predict earthquake by using data is a new probe of geochemistry methods,so this work provides real observation base for its deep going study.