The current global consumer market is developing in the direction of digitalization, and international e-business incorporation also has to face the proposition of digitalization and make adjustments in international express. The orderliness of the two subsystems of international e-business and international express in China has been growing year by year, while the synergy of the composite system has been relatively low and belongs to a low degree of coordination. This paper takes international e-business and international express as the research objects, uses composite system theory and synergy theory, measures the synergy between international e-business and international express nationwide by establishing a composite system synergy evaluation index system, and analyzes the reasons for the lack of synergy between the two, and puts forward countermeasure suggestions to realize the synergistic development of the two, which is of great significance to innovate the operation mode of international express, build an integrated e-business platform, and promote the coordinated development of international e-business and international express in China.