To solve current stiffness problems of long-span cable-stayed bridges,a new cable-stayed bridge with carbon fiber reinforced polymer(CFRP)and steel composite stay cables was proposed.Firstly,the de-sign strategies and procedures for the proposed cable-stayed bridges were introduced.The equations to calcu-late the material amounts and costs of the proposed cable-stayed bridges were also derived.By doing this,the economic behaviors of the composite bridges,which were the emphasis of this paper,were then studied.A parametric study with regard to span length,pylon height,and cost ratio(the cost ratio of CFRP stay cables to steel stay cables)was finally conducted,which determined the developing trend of economic behaviors.It is proved in this study that the application of CFRP and steel composite stay cables in cable-stayed bridges is fea-sible from the economic viewpoint and the proposed composite cable-stayed bridges could become an excellent alternative to the traditional cable-stayed bridges in the future.