DCM is a common ground improvement method for strengthening revetment on soft foundation. It is a common way to analyze the overall stability of revetment adopting composite foundation comprehensive strength design method. In some cases，the results of overall stability by the above method can satisfy the requirement of codes，but sliding accident happened. Thus the applicability of this method in revetment design needs further analysis. Focusing on a failed engineering project，we applied composite foundation comprehensive strength parameters，strength index of DCM piles and original soil parameters between DCM piles respectively to check the stability of revetment by software Plaxis 3D，and by changing the shearing strength of soft soil and replacement ratio of DCM，we analyze comparatively their influence on the overall stability. The results show that under the condition of low shearing strength of soft soil and low replacement ratio of DCM，the DCM composite foundation comprehensive strength method has a poor applicability in revetment design. It means comprehensive strength method can’t equivalently reflect DCM’s strengthening effect on very soft soil foundation.