Abstract：In the construction of civil engineering，the local environment will be destroyed. Not only is the greening project advantageous to resume the natural environment destroyed，but also the roots of vegetation will strengthen the surface of slope. In respect of vegetation growing，the slope is reclassified；the roots protection mechanism is studied. Then the stability of the protecting layer is studied by test and numerical simulation. The results show that the effect is different for different structures of rock mass. In order to guarantee the stability of the protecting layer of slope，according to the classification，height and slope rate，the proper methods with other measures should be applied.
