Deterioration mechanism of concrete suffered slowly freeze-thaw and eroded in different mixed liquor (3%NaCl+5%NaSO4, 3%NaCl+1.5%NaSO4, 5%NaSO4, water) were experimental investigated. The hydration product and microstructure of concrete specimen after 100 circles of freeze-thaw was tested and analyzed with SEM (Scanning Electron Microscope). The result indicated that under the interactions of freeze-thaw and mixed erosive solution, there were not only physical changes but also chemical reactions occurred in concrete, which exacerbate the mechanical properties deterioration of concrete. The mechanical performance and microstructures of concrete deteriorated most significantly in the mixed solution 3%NaCl+5%NaSO4, and deteriorated more significantly in the mixed solution 3%NaCl+1.5%NaSO4.