Abstract: Based on existing Hamiltonian method for eigenvalue calculation of normal mode, an efficient method for broadband eigenvalue calculation is developed. Hamiltonian method gets rid of the frequency term by formula transformation to change the root finding problem from a three-dimensional problem with respect to frequency as well as real and imaginary parts of eigenvalue into a two-dimensional one. As a result, the eigenvalues of singular normal mode corresponding to all frequencies could be solved at one time. A MATLAB parallel computing method and other optimizations are included to improve the computational efficiency of Hamiltonian method. The significant advantage of Hamiltonian method in efficiency is indicated by several numerical simulation comparisons with KRAKENC, while retaining the same accuracy.