As the material carrier of international trade, the shipping network that has been formed between China and the countries along the Belt and Road is an important support for the prosperity and development of the Maritime Silk Road. In this paper, a complex network model was used to characterize the port shipping network between China and the countries along the Maritime Silk Road in 2008 and 2018. Then, the coupling characteristics of the network and trade of various countries were analyzed by constructing an index system to reveal the shipping network's ability to support trade. Finally, spatial heterogeneity of influencing factors was analyzed by using geographically and temporally weighted regression model. The results show that: (1) on the whole, the port shipping network in 2008 and 2018 had obvious complex network characteristics. Network density increased by 111%, while its overall operating efficiency decreased by 8.73%. (2) The coordination degree between the shipping network and trade increased by 5%. It is also noted that most well-performed countries were distributed in East Asia and Southeast Asia. By 2018, about 36% of the shipping network of countries along the Maritime Silk Road lagged behind the level of trade, resulting in a significant shortage of shipping support. About 28% of the shipping elements of countries along the route were oversupplied. Most of the remaining countries evolved from low-level coordination to intermediate coordination. From a regional perspective, the coordination of these countries had obvious space club convergence. (3) There were obvious regional differences in the factors influencing the coupling relationship. In general, the scale of trade, the efficiency of port shipping and the economic benefit of foreign trade are the most important factors that promote the synergy effect of the shipping networks and trade, while the coverage of liner routes, port transit capacity and trade barriers are not so influential.