Abstract: Interpreting the hydrological dynamic change law of critical karst zones is of great significance for the understanding of karst water circulation mechanism and the sustainable utilization of groundwater resources in karst areas. Taking a typical karst area of the Yellow Dragon Spring in Aziying Township, Kunming City as the research area, the hydrometeorological data of the meteoric precipitation, drop of different types of caves and spring water were continuously monitored weekly. Based on the monitored data, the annual hydrological dynamic change characteristics and rules of the evolution from precipitation to cave water drop to spring water in karst area were revealed using time series method and the indices of annual non-uniformity coefficient, complete regulation coefficient, concentration degree and concentration period. The results show that the indexes of annual non-uniformity coefficient, complete regulation coefficient and concentration degree showed a vertical decrease from precipitation to cave water drop to spring water, among which the sensitive drop≤stable drop＜seasonal drop. The concentration period of water drop and spring water in the cave was about two months later than that of precipitation. The retention effect of cave water drop and spring water on precipitation and the response time were sensitive drop＜spring water≤seasonal drop＜stable drop. The water in the critical karst zone changed frequently from abundant to scarce and vice versa seasonally, and it presented the characteristics of hydrological zoning of vertical migration from precipitation to cave water drop to spring water. It indicates that the Yellow Dragon Spring is supplemented by point, linear and planar sources, and it is a constant karst spring with large seasonal fluctuations.