Abstract: Abstract：According to different hydrogeological and characteristics of karst areas as well as the characteristics of groundwater circulation and by applying the systematic analytic method, the karst water systems may be classified into three grades: the first grade is the karst water system; the second grade includes the shallow-circulating and deep-circulating karst water systems; the third grade may be further divided into six basic karst hydrogeological units or types, exposed, exposed-covered, exposed-buried, perched water, deep-buried stratabound and fault zone types. The paper also discusses the hydrogeological characteristics of the various types and points out the significance of various systems in water supply. This study is of reference value for the exploration and development of karst water resources in down-faulted basins.