The contribution of matric suction and stabilizing piles to the global stability of unsaturated soil slope should be properly evaluated in practice. Methods of design and analysis for slope reinforced with piles are firstly discussed and reviewed. Then
by making use of the strength reduction finite element codes
the global stability of unsaturated soil slope are analyzed. Four cases are combined according to the conditions of stabilizing piles and matric suction. The comparison of results can evaluate quantitatively the effect of matric suction on slope.