water resources of inland watershed in arid region are formed in the mountainous area, the upper reaches, utilized and consumed mostly in the oasis for agricultural irrigation in the middle reaches, and exhausted in the desert area for the natural river and terminal lake ecosystem sustaining in the lower reaches. Due to the characteristics of the hydrological cycle in the watershed, the water regime can be divided into water-yield area, waterconsume area and water-formed area in the upper, middle and lower reaches, respectively. These basic natural features determined and controlled the water regime process in the inland watershed in temporal-spatial scale. The water regime process and its driving mechanism on the varied temporal-spatial scales in the mountain area of upstream, oasis of middle stream and desert area of down stream in the Heihe river basin, which was the representative inland watershed in the arid regions in northwest China, was studied and summarized based on many scholars' works of the last decades. By comparing to the varied proxies of the ancient environmental changes, the result showed that the water regime process presented similar trend in the special period on large scales in the upstream and downstream area, while the temporal-spatial heterogeneity on small scales. To the driving mechanisms, the effects of the climate change and human activity on the water regime process in the upper, middle and lower reaches of the Heihe river was in different weightiness. And the two factors presented the coupling model in different temporal scales. In the nearest future, it needs more works in the water regime process on basin scale as follow: (1) to reconstruct the water regime process in the water-yield area systematically by the ice core and tree-ring record, especially in the area in the west upper branch of the Heihe river due to its water contributions to the lower reaches before 1940′s. (2) to pay more attention to the oasis evolution in the middle reaches that was driven by the government policies, population changes, agricultural technique development and its related population capacity changes of the water resources and climate changes. (3)to understand deeply the relationships between the water resources and the natural oasis changes based on the study of the environment changes in the period of the last 500 years and recent 50 years which was the increasing and maximum periods of the human activities.