The spring hydrograph is composed of the cumulative rainfall, baseflow, and quick flow based on the characteristic of the karstic aquifer. A linear convolution integral model is applied to distinguish the quick flow and slow flow component of a karst spring hydrograph. Different from the traditional unit hydrograph methods, the two parallel reservoirs are used to derive the unit response functions for quick and slow components of spring hydrograph. The method also provides an estimation of the parptitioning coefficient assigned to the reservoirs. The work is demonstrated by a case application to the Houzhai underground river in southwestern of China. The result shows that the proportion of conduit flow is smaller from the upstream to the downstream. However, this approach is not established in the large basin or the long- term forecast of the spring discharge.