The stability of a submerged dyke body is the difficult point in the design of a plastic -  soil -  pillow submerged dyke. By the analysis of the forces acting on the submerged dyke located at the entrance of left branch of Hechangzhou river -  branch in the Zhenjiang -  Yangzhou stretch, the calculations on the stabilities of various locations of the submerged dyke were performed. The calculated results indicated that all stability factors are more than 1.5. Through over one year operation and monitoring, it is stable, and its expected targets are good.