[Objective] The factors affecting landscape ecological risk in karst watersheds were determined in order to formulate ecological risk prevention and control measures and landscape management planning in mountain watersheds. [Methods] This study was conducted in the Guizhou section of the Hongshui River basin (a typical karst basin). The study utilized the perspective of “productive-living-ecological” space, and used GIS spatial analysis, landscape ecological risk index, and other methods to explore the temporal and spatial change mechanism of landscape ecological risk in the study area. The relationship between the temporal and spatial distributions of landscape ecological risk and topography was analyzed by means of the distribution index method. [Results] ① Since 2000, land use transformation based on the productive-living-ecological space in the Hongshui River basin was characterized by a reduction in the production and ecological space and a rapid increase in the living space. The contribution rates of regional landscape ecological risk changes caused by the transfer of different land use types were different. ② During the period from 2000 to 2020, the overall landscape ecological risk showed a moderate trend, and the landscape ecological risk in the southern part of the Hongshui River basin was generally better than in the northern part. ③ From the distribution of landscape ecological risk on the terrain gradient, the degree of landscape ecological risk was inversely proportional to the terrain gradient. In addition, the landscape ecological risk in the non-karst area and pure karst area was lower than that in the subkarst area. [Conclusion] Although the landscape ecological risk in the Hongshui River basin has improved, some landscape ecological problems are still prominent, and it will be necessary to strengthen the management and protection of the ecological environment.