研究了含有中间层的流体系统的双界面KH 不稳定性。计算发现：由于耦合作用，界面KH 不稳定性呈现出不同的增长模式。主要研究了对增长率影响最大的夹层厚度对增长模式的影响，发现厚度小于半个扰动波长时，耦合作用必须考虑。另外发现在特定厚度下，界面不稳定性将出现简并的增长模式。“,”Characteristics of the Kelvin-Helmholtz (KH)instability of the interfaces formed by two semi-infinitely distributed fluids and one interlayer were studied.It was found that the coupling effects between the interfaces should be considered if the interlayer thickness was less than 0.5 times of the disturbation wave-length.And the degenerate modes could be produced in the situation with proper parameters.