Abstract: The bifurcation of parallel plate-type beams with cubic nonlinear stiffness in inviscid fluids was investigated. A nonlinear model for a simply supported plate-type beam in inviscid fluids, a solid-liquid coupling system, was established on the basis of the hypothesis that all the plates have the same deflections at any instant. An algebraic criterion ofHopf bifurcationwas used to analyze the bifurcation ofthe structure. The result shows that there is no Hopf bifurcation for the structure in inviscid fluids. Finally, the static bifurcation of equilibrium positions and local stability of the structure were discussed. The numerical simulation shows that the coupling system is a nonlinear conservative system.