Large-scale artificial plantations in mountainous areas of Southwest China have changed land use status and aggravated land degradation risk (LDR). This study taking Menglian County as an example, optimizes land use in 2025 to reduce the regional LDR, by integrating Grey Linear Programming (GLP) and CLUE-S model. Results showed that: The high-risk and medium-risk levels are main LDR types in Menglian County, accounting for 56.36% of total area. The regions with high LDR consistent with the distribution of concentrated garden land and cultivated land. The regions with low LDR consistent with the forestland. While the distribution of medium-risk regions relates to small plots garden land and cultivated land. In the optimization results, the LDR reduced 461.80, 168.95 and 34.23 in three schemes respectively, comparing to 2015. Thereinto, the strict-demand scheme has good applicability and guidance for study area relatively, in which the LDR is reduced while ensuring sustainable development. After spatial allocation, garden land, cultivated land, forestland and construction land tend to be centralized. It is effective for solving the optimal problem of mountainous land resource by integrating GLP and CLUE-S. The methods and results can provide a scientific reference for controlling LDR in mountainous area in Southwest China.