[Objective] The Qingshui River watershed in the upper reaches of the Haihe River is located in a fragile ecological region where climate varies from arid to semiarid. The spatiotemporal variation of land use in this region was studied for local decision making on ecological construction.[Methods] Based on land use data interpreted from Landsat remote-sensing images at four periods during 1990-2018, the land use changes of the Qingshui River watershed were analyzed and predicted by using the logistic-CA-Markov model under an optimal space scale.[Results] ① During the past 30 years, the land use of the Qingshui River mainly consisted of cultivated land, forest land, and grassland, and the total area of these three land use types accounted for more than 96% of the study area. The area of construction land increased, and its change intensity was the maximum. ② The receiver operating characteristic (ROC) value of each land type reached the best level at a scale of 100 m×100 m, which was obtained based on the goodness-of-fit tests for ROC curves. ③ The area of grassland and water area would decrease by 42.44 and 5.43 km², respectively, from 2018 to 2027. The areas of cultivated land, forest land, and construction land would increase by 16.51, 16.89, and 14.67 km², respectively.[Conclusions] ① The scale of 100 m×100 m was the suitable space scale for the prediction simulation on a typical small watershed, such as the Qingshui River watershed. ② The preparations for the 2022 Winter Olympics drastically accelerated the exploitation intensity of construction land, and they were the dominant driver of the land structure change in the Qingshui River watershed.