Abstract: By means of mechanics of sediment transport, forces acting on soil grain are analyzed under the slope surface flow and calculation formula of critical gradient is set up. Based on the critical gradient, the design of high cutting loess slope is studied considering the optimizing of slope grade, the determining of slope height and the constraining of platform. The analysis results of engineering example show that the design method of high cutting loess slope considering slope surface stability is rational. Thus, it is proposed that the excavation grade and shape of slope are not only satisfied with slope stability but also satisfied with slope surface stability when slope is excavated.