As the treasure repository for mankind, the largest transportation corridor, as well as the strategic buffer zone of the coastal states, the ocean plays a significant role in the development of human society. Recent research on the ocean mainly focuses on comprehensive marine strength of countries, and few papers discussed the marine dependence, not to mention the coordination between the two aspects. Therefore, it is difficult to make scientific predictions on the trend of the comprehensive marine strength. The paper takes China and America as research objects, and builds evaluation index systems as well as the coupling analysis model for comprehensive marine strength and marine dependence. The conclusions are: 1) Marine dependence of America dropped consecutively in the recent 10 years, while that of China increased a lot and surpassed America in 2010. Comprehensive marine strength of America is at a steadily high level, while China witnesses a rapid development of comprehensive marine strength, which had a low starting point, and the gap between the two has diminished in the past few years. 2) The descending marine dependence of America appears digressive coupling relationship with the stable comprehensive marine strength, which restricts the development of American ocean system, indicating that America is entering a shrinking stage of marine strategy. 3) The coupling relationship between the two dimensions of China shows a favorable trend, and it is beneficial to promoting Chinese marine influence and ensuring the safety of Chinese marine dependence.