In the previous analyses of retaining wall stability， it was assumed that the backfill soil behind the wall was saturated soil， and the influence of the suction stress effect on the sliding stability of the retaining wall was ignored， which led to the distortion of the calculation results. In view of this， based on the generalized effective stress principle， the work-energy balance equation applicable to unsaturated soils was derived， and on this basis， a method for calculating the upper limit stability coefficient for anti-sliding of the retaining wall-unsaturated soil system was proposed by using the energy method. The rationality of the method in this paper was verified by comparing the results of OptumG2 numerical software and the existing theoretical methods. And the influence of parameters such as soil shear strength， air-entry value， and seepage flow on the stability of the retaining wall was discussed. The research results show that： 1） Compared with sand， suction stress has a greater impact on the stability of retaining wall in clay， while the change of cohesion in the sand is more sensitive to the stability of the wall-soil system； 2） With the increase of air-entry value， the contribution of the suction stress to the stability of the wall-soil system decreases and eventually tends to be constant， and the influence of the suction stress on the low retaining wall is more obvious； 3） Compared with the case without suction， the stability coefficient considering suction is larger， the influence of different seepage flow on the stability of the wall-soil system is as follows： evaporation> no flow> infiltration， and the seepage flow has the greatest influence on the stability of retaining wall in clay and silt， followed by loess and sand.