Abstract: China's 11 coastal provinces have not only the regional advantage of "marine economy", but also the institutional advantage of "free trade pilot zones". In order to deeply study the impact of the two advantages' interaction on regional economy, this paper constructs a coupling and coordinated development model between "marine economic development" and "development of free trade pilot zone" in 11 coastal provinces of China. Our research shows that the higher level of coupling and coordination between the two a region has, the better economic development the region will enjoy. This paper demonstrates the great significance of coordinating the two factors to coastal economic development. As the model shows, the coupling and coordination coefficient in the past 8 years averages at 0.7616, which means the two are coupled and coordinated only to a medium extent and need to be improved. At the same time, it is also found that there is strong regional heterogeneity, the degree of marine economic development in more developed areas does not match the economic and trade level, the coupling development level of the newly established pilot free trade zone is greatly impacted by COVID-19, and Hainan free trade port is at the worst level in China. Therefore, this paper puts forward targeted countermeasures and suggestions on the basis of this analysis.

Key words: marine economy, free trade, coupling and coordinated development, Hainan free trade port