Abstract：The ecological technique has been widely applied to the protection of the red bed slope recently；nevertheless the red bed mudstone slope ecological protection theory is not systematically studied. By selecting the typical red bed mudstone slope，the mechanism of the ecological protection of the fast weathering of the red bed mudstone slope surface is studied by the field rainfall tests with the ecological protection and without it and the long-term monitoring tests on the temperature field and the moisture content of the shallow layer of red bed slope. It is concluded that the ecological protecting functions on the fast weathering of the red bed mudstone slope include eliminating the weathering material erosion and changing the temperature field and the moisture content of the shallow layer bed mudstone slope. More importantly，the ecological protection prevents the red bed mudstone slope surface from rain，making no high difference in temperature and the thermal stress in the shallow layer. So，the fast weathering of the surface is eliminated.
