Generally speaking,the background shear current U( z ) must be taken into account in eigenvalue problems of nonlinear internal waves in ocean,as is different from those of linear internal waves. A numerical calculation method for eigenvalue problems of nonlinear internal waves is presented in this paper on the basis of the Thompson-Haskell's calculation method. As an application of this method,at a station(21oN,117 o15′E) in the South China Sea,a modal structure and parameters of nonlinear internal waves are calculated,and the results closely agree with the calculated results based on observation by Yang et al.
