This paper studies a pricing discrimination strategy of competing firms with service differentiation-behavior-based pricing (BBP). We use game theory to construct a two-period dynamic pricing model. Through the comparative analysis of prices and profits, we explore firms' optimal pricing strategy. We analyze the interaction between BBP and service differentiation. Main conclusions are as follows: 1) Two major factors, service differentiation and relative service cost, interactively affect firms' optimal pricing strategy. Specifically, when the degree of service differentiation is low (high) and the relative service cost is small (large), competing firms don't adopt (or, adopt) BBP. When the degree of service differentiation is low (high) but the relative service cost is large (small), competing firms have mixed strategic Nash equilibrium, and both parties have a certain probability of adopting BBP. 2) In the case of mixed strategy Nash equilibrium, the fierce price competition caused by BBP does not always harm both competitors' profits. When the degree of service differentiation is low and the relative service cost is large, high-service-level firms can gain more profits. 3) When the degree of service differentiation is high and the relative service cost is relatively large, the interaction between BBP and service differentiation can realize the Pareto improvement of profits for comepeting firms and they can achieve a win-win situation.