Abstract: The runoff-drainage area of Niangziguan spring is mainly distributed in Yangquan City,Shanxi Province.Karst water of the spring is an important water supply for the city.The results of the assessment of the water quality variety through runoff-drainage area show that the karst water is seriously contaminated with the main pollutants of SO^2-₄,TDS and total hardness.The content of SO^2-₄in the karst has indicative significance for pollution source discrimination of total hardness and TDS.Applications of sulfur isotope(³⁴S)calculations show that mining is an important cause of water pollution of the karst water.The comparison of the present water quality with the water quality of 2003 demonstrates that the surface water and karst water from coal sulfur increases in the proportion of SO^2-₄,and this increase rate is maximum especially in karst water of the drainage area.