Rubble mound breakwater and vertical breakwater are the common forms for breakwater structures，and the cost of the project is the important factor to be considered in the structure selection when the two structures are used for comparison and selection in the design scheme. This paper combines with an actual engineering case，analyzes the impact on the project cost based on natural conditions，main material supply，construction difficulty degree，and construction period requirements. The results show that when the water depth is shallow and the stone source is abundant，the rubble mound breakwater has the advantage of lower construction cost. For the large water depth and special landscape requirements，vertical breakwater can be selected.