Abstract: The WKBZ approximation with the surface phase-shift correction, which hasadvantages of concise form and easy calculation,is used to compute mode eigenfunctions. Onthe basis of the WKBZ eigenfunction,a mode approach is proposed. This approach has beenapplied to sound propagation in the North Pacific,and a great number of numerical examplesare given. The results show that the WKBZ mode approach is a fast and accurate numericalmethod to calculate the acoustic field of convergence zones in stratified ocean channels