Conduit flow is a special geomorphologic and hydrological phenomenon in karst area. Houzhai River drainage basin in Puding, Guizhou Province is a large-scale test field in the main and broad karst area in the southern part of China, where conduit flow is a general reserve and drainage system for groundwater. Based on the great deal of field investigation and indoor research work during the 1970s-1980s, pulse tests were done four times there during 1988-1991 in wet and dry seasons. It shows that water level at each observation site changes from 10 to 1800 mm, with the larger variation in upper stream and at karst windows than in lower reaches and at each exit along subterraneous rivers. The average flow velocity in conduit system is determined within 200-800 m/h, with the less change from flood to dry seasons, and it is higher in principal conduits and in upper stream area. Also, the reliable divided discharge ratio among each hydrological conduit of sunken system has been got. Thus, combined with detaile Conduit flow is a special geomorphologic and hydrological phenomenon in karst area. Houzhai River drainage basin in Puding, Guizhou Province is a large-scale test field in the main and broad karst area in the southern part of China, where conduit flow is a general reserve Based on the great deal of field investigation and indoor research work during the 1970s-1980s, pulse tests were done four times there during 1988-1991 in wet and dry seasons. It shows that water level at each observation site changes from 10 to 1800 mm, with the larger variation in upper stream and at karst windows than in lower lower and and at each exit along subterraneous rivers. The average flow velocity in conduit system is determined within 200-800 m / h, with the less change from flood to dry seasons, and it is higher in principal conduits and in upper stream area. Also, the reliable division discharge among each hydrological conduit of sunken system has been got. Thus, co mbined with detaile