This paper is the result of ecological environment geological survey engineering. Objective The Qinhe River Basin serves as an important water–receiving area and soil–water conservation functional area in the middle reaches of the Yellow River. The main water catchment area in the upper reaches of the basin mainly covers two counties, Qinyuan and Anze. Scientific analysis of the temporal and spatial variation characteristics and influencing factors of its water conservation capacity can provide technical basis for the ecological environment restoration in the middle and lower reaches of the Qinhe River and even the entire basin, as well as for the ecological protection and high–quality development planning of the Yellow River Basin. Methods This paper uses the water balance method to analyze and discuss the spatiotemporal dynamic change characteristics of the water conservation function of the ecosystem in the region during the 30 years from 1990 to 2020 and the influence of different factors on the water conservation capacity.According to the regional water conservation capacity and combined with the distribution of natural protected areas within it, the importance level of regional water conservation is divided. Results (1) In terms of space, the water conservation capacity in the study area shows a pattern of being high in the south and low in the north, high in the middle and low around, with significant regional differences. The average value of multi–year water conservation volume is 366.74×10⁶ m³.The change trend of water conservation function in nearly 30 years shows a characteristic of first decreasing and then increasing. (2) Climate factors have a strong correlation with water conservation volume, and vegetation types also affect the spatial characteristics of water conservation.Among vegetation types, forests are the main body of water conservation in the ecosystem within the region. However, in terms of water conservation capacity, shrublands are higher than forests and grasslands. (3) The total area of important and important–highly water conservation areas in the study area is 733.38 km², accounting for 35% of the total area of the study area.The total amount of water conservation of the two accounts for 53.63% of the whole area. They are mainly distributed in the small and medium–sized undulating mountains in the transition between the two sides of the river and the large undulating mountains and the southern area of Anze County. It is the concentrated area of water conservation in the entire study area. Conclusions For the construction of water conservation capacity in the upper reaches of the Qinhe River Basin, some ecological governance measures are proposed, including identifying the Lingkong Mountain and Huapo areas as extremely important areas for water conservation function. According to local conditions, tree species with strong water conservation capacity can be increased, and the governance and restoration of subalpine meadows and temperate grasslands can be strengthened.