Abstract: When simulating tsunami etc.,only around the place where the disaster occurs,full three-dimension simulation is needed.At the other places,two-dimensional wave simulation can be used.To effectively use the computing resources for solving this kind of problem,a new algorithm based on the region coupling is proposed.By the algorithm,the whole computing region is divided into complex regions and simple regions,where the three-dimension Navier-Stokes simulation and two-dimension wave simulation are used respectively.Along the boundary of complex or simple regions,related variables are extrapolated from the other regions.As a result,the physical information can be exchanged between different regions and the computing regions are tightly coupled.Finally in this paper,an example of wave creation and propagation is given to show the feasibility of the algorithm.