On the basis of investigation and research on the pollution source and pollution pathway of Yujiagou area, by the ground water quality analysis and the leaching and soaking experiments of the gangue, reliable data were obtained. The experiment results prove that these inorganic salt elements are easily dissolved by the water. The main pollu-tion factors in the ground water are consisted with the main pollution factor in the leading water of the gangue. By synthetically analyzing, a conclusion is shown that the salts in the leacheate of the waste dump of open pit coal mine are the primary pollution source for groundwater of Yujiagou area. An assessment is made about the degree of pollution of the ground water in the study area.