Abstract: There is lots of mined-out area in Beijing Fangshan region due to mining building stone, which is a kind of adverse geologic actions in highway construction. Stability evaluation and treatment on subgrade of highway in mined-out area is quite difficult because of no planning, disorderly, and repeatedly excavation, the distribution and complicated boundary conditions of mined-out area. This article used the criterion mining conditions method, limit equilibrium analysis method, collapse self-obliteration method and the protodyakonov's theory to discuss the stability evaluation and treatment measures for a mined-out area of Jingshi second highway(Da yuan village～Beijing municipal boundary).