Based on the principle of the slope plant protection and reaction way,with the help of the hydraulics and sediment corrosion theory and formula,calculation ways for the function effect of the slope plant protection are obtained,the canonical calculation way for the ability of the slope plant protection is inexistent.Through the mechanics calculation of the slope plant protection,as well as the defended corrosion capability under the plant protection by use of the sediment corrosion calculation,the function of plant protection is verified.Then the application of the slope plant protection is expanded further.