Due to the containerization of international sea transportation and the uprising containership size, the inter-port competition is getting intensive. Nevertheless, most of the research related to the port competition have focused on the empirical studies. In contrast, research on the development of theoretical-oriented derivatives is quite scarce. This paper has developed a theoretical model to demonstrate the competitive behaviors among ports. Furthermore, the findings followed on the derivatives of this paper are expected to shed some light on the strategies of port competition with theoretical basis.