Aiming at the competition and cooperation decision-making problem between two ports in the same regional port group, this paper studies four kinds of dynamic game scenarios of two adjacent ports—namely, independent strategy–independent strategy (i.e., DD combinations), independent strategy–integrated strategy (i.e., DT combinations), integrated strategy–independent strategy (i.e., TD combinations), and integrated strategy–integrated strategy (i.e., TT combinations). By introducing port demand models and using the dynamic game method, the paper performs a comparative study of port service pricing, port demand, and port profit in different combinations of competition and cooperation. The results show that taking port profit as payment function, the equilibrium strategy of the leader port is the independent strategy, which is also the dominant strategy, while the independent strategy or integrated strategy of the follower port depends on the degree of service substitution provided by the two competing ports. When the degree of service substitution is low (0 < γ < 0.53), the equilibrium strategies of two competing ports are the DD combinations, but the equilibrium strategies can be improved by Pareto, and further analysis shows that TT combinations are the Pareto equilibrium strategies at this time. By contrast, when the degree of service substitution provided by the two competing ports is high (0.53 ≤γ < 1), the DT combinations are the equilibrium strategies of the two competing ports, which are also the Pareto equilibrium strategies at this time. The research shows that when the degree of service substitution of the two ports is low, to encourage the two ports to carry out differentiated development of service functions, it is conducive to promote the two ports to adopt the integrated cooperation strategies.