(1) Sea power is closely related to the rise and fall of a country. Mahan put forward a concept in the book, namely sea power. Sea power is everything that can make a nation become a great nation by virtue of or through the ocean. Mahan's statement expanded the connotation and extension of sea power to the greatest extent. The sea power he said should include maritime military forces and non-military forces. The former includes the owned fleet, including affiliated bases, ports and other facilities, while the latter includes marine-related affiliated institutions with overseas trade as the core and their capabilities, that is, the sum of the national marine economic strength. In terms of material form, sea power is actually a country's comprehensive strength in the ocean. The establishment and development of a powerful maritime force is of great significance for promoting national economic prosperity and wealth accumulation, seizing the right to control the sea and winning maritime wars, and safeguarding the country's international political status. From this perspective, sea power not only marks a country's overall ability to use and control the ocean, but also determines whether a country and a nation can become a great nation. So Mahan's sea power theory is actually a theory about how to control the world by seizing sea power. (2) Six factors affecting sea power. The first is geographical location. For example, island countries do not rely on land for self-defense or territorial expansion, but aim at the ocean completely. Compared with mainland countries, island countries have a clearer strategic goal of developing into the ocean and have superior conditions for developing sea power. The second is the natural structure. Countries committed to the development of sea power must have a long coastline, many deep-water ports that can be protected, and rivers that go deep into the mainland. The third is the territorial scope. The development of a country's maritime power must rely on a certain area of territory, and the size of the territory should be adapted to the number, resources and distribution of the country's population. The fourth is population. The population is mainly engaged in marine undertakings, which can provide sufficient troops for the development of the navy. Fifth, national characteristics. The people of a naval power must be eager for material benefits and pursue profitable business exchanges at home and abroad, which can also be summarized as the national spirit of a nation's strong pursuit of overseas colonies and overseas interests. Sixth, the nature of the government. The government should have a sense of the ocean, attach importance to the navy, and have continuity in its policies. (3) The relationship between sea power and land power. Mahan believes that sea power and land power are interdependent and interdependent, and he attaches great importance to the significance of "relying on" land for sea power. (4) The use of sea power must abide by the "laws of war". In his book, Mahan explained some important principles in detail with a large number of war cases, such as the principle of concentrating superior forces, destroying enemy communication lines, fighting for the fleet, and the principle of central position.