Breakwater top elevation is one of the main factors determining the breakwater cost. In order to control the investment, this paper calculates the top elevation and model validation using oblique wave reduction, and by wave run-up method. It is concluded that the reduction of the breakwater top elevation has little impact on the inner-harbor mooring conditions under 2-year frequency wave action. Therefore, to determine the breakwater top elevation, we shall consider its functional characteristics and utilization and protection requirements to select appropriate breakwater elevation control standards and calculation methods, and then determine the top elevation of the breakwater.