Abstract: The aim of this study is to understand the longtime underground water quality variation characteristics in karst regions. Choosing karst underground water of central Guiyang city as the object, the variation characteristics of karst underground water quality of Guiyang in 30 years were analyzed using 48 samples collected in 1984 and 2014, respectively. The results show that the ground water quality is good as a whole, while having a tendency to deteriorate. Only 9 sampling sites of 1984 were not suitable for drink directly, which was mainly caused by primary background environment. In 2014, 14 sampling sites were not suitable for drink, most of which was caused by human activities. The hydrochemical types of underground water have changed greatly over the 30 years, about half of the controlling points were changing into the HCO3·SO4 type from the type of HCO3 Underground water was getting sulfation obviously. Underground water quality in old and new city zones were getting better, and that in rural-urban conjunctions was easily polluted. Due to the low degree of human activities , the water quality in agricultural areas were changing gently. In the work of groundwater resources development and environmental protection, karst hydrogeology conditions and human activities characters in different areas should be considered synthetically and the objective-oriented evaluation of monitoring and management should be carried out. Aiming at the phenomenon of groundwater salinization in the work area, the comprehensive improvement of the urban-rural conjunctions should be strengthened to facilitate comprehensive protection of the groundwater environment in agricultural areas, so as to curb the trend of groundwater pollution and prevent the occurrence of groundwater pollution incidents.