The U.S. government has always attached importance to the formulation and implementation of marine development strategies and policies. Benefiting from the developed and abundant marine resources of the mainland economy， its marine economy has been rapidly developed and the United States has gradually become a marine economic power. Based on the ENOW source data in the NOEP database， this paper studies the leading industries and the characteristics of the current situation of the U.S. marine economy and makes a prospect of the development trend of the marine economy in the United States considering the development environment and the limiting factors. This article argues that the U.S. government should continue to increase investment in the tertiary industry in the oceans， support the traditional marine secondary industry and promote the development of marine emerging industries.