The quantities, the distributing characteristics, the variation law and the mutual transformation relationship of surface water resources and ground water resources in the Hexi inland arid region of Gansu Province are analyzed on the basis of the hydrological and meteorological measured data at the concerned hydrometric stations and weather stations, and the related research achievements of National Science and Technology Tackle Key Problem Item (project 96-912). The results show that the surface runoff mainly are formed in the middle and the high mountainous area in the inland arid areas and dissipate in the pediment plain and desert.  The supply of runoff mainly is atmosphere precipitation, ice and snow melting water and ground water. The quantity and temporal and spatial distribution of precipitation possess quite important effect to water resources forming in the region. There the mutual transforming relationship between surface water resources and ground water resources is quite clear. The most primary characteristic of water resources in inland arid region just is the mutual transformation between the river runoff and the ground water in the different geology and physiognomy cells from the mountainous area to plain area. The transforming relationship among surface water resources, ground water resources and the flowing mode are dissimilar in the different regions from the runoff forming situated the mountainous area to the lower reaches situated plain and desert, that is, the most of the mountainous area ground water formed by ice and snow melting water and precipitation is excreted in the form of the base runoff and entered into the basin in the form of the surface runoff.  Surface runoff largely supplies groundwater again after rivers enter into the basin or the pediment plain which penetrating power are quite strong.  Ground water in the basin or the pediment alluvial and diluvial plain largely overflow from the surface and inflow into river to transform as river runoff again after they flow from the pediment plain to the edge zones of pediment fan s along terrain and slope.  The flow of runoff is slow and the movement of groundwater basically is vertical in alluvial plain below the pediment alluvial and diluvial fans. Under nature, river rushes down flood and supplies groundwater by river ways, and that the residual river runoff flows into the sink lakes from lower reaches of the wash plain to the sink lakes in the flood season. The rivers runoff is little even none during non-flood season. It is the small quantity rivers runoff and the groundwater formed by it that maintain the oasis of the lower reaches area of rivers in the inland arid regions in the northwest China and quite flimsy zoology environment here. The characteristic of the transformation processes between surface water and ground water affects directly the water resources development of the regions. At present, the quantity of output spring is being decreased even has dried up because of developing economy and developing water resources on a large scale in the upriver areas. The former spring irrigation areas have had to be changed well irrigation areas along with the utilization rate of surface water being improved continually and the supply of ground water being decreased continually.  The ground water in lower reaches of rivers in the alluvial plain is difficult to be supplied with surface runoff from the upriver areas even in the flood season, which lead to the continual descent of ground water level, the death of the vegetation and the desolation of the land. So the development and the utilization of the water resources should possess a uniform and rational layout in the inland arid regions. Summarizing the experiences of the various areas and working up the optimization water resources utilizing mode of the various areas will possess a quite important meaning on the development and utilization of water resources in the inland arid region for the future.