Abstract: In an attempt to study various phenomena supposedly to be precursory to an impending earthquake in China, variation of the hydrochemical effect of ground water are now observed. Experiment by utilizing mine blasts is merely aimed at finding some indications to show that impulsive force acting on the crustal medium can give rise to any changes of chemical contents of underground water in order to provide certain evidences for this phenomenon to be a possible earthquake precursor.This article deals mainly with a study of a large amount of hydrochemical observational data obtained in a series of three blasts at the Yongping copper mine of Jiangxi province as regards to the characteristics of the hydrochemical effects It has been shown that the dilatational impulsive forces from a blast is the principal cause of variation of the radon and other hydrochemical components of ground water, and the differences of the geological, hydro-geological and geochemical conditions of each observational well site can modify the effect by strengthening or weakening it. The results of this study provide also experimental basis for reasonable selection of the wells (or springs) in the studies of variation of hydrochemical components in ground water by changes of stress.