Abstract: Xi Jinping’s thinking and practice on understanding, valuing and developing the ocean during his work in Fujian province is an important basis for Xi Jinping’s important discussion on building a powerful country in the ocean. It is also an important part of Xi Jinping’s discussion on building a powerful marine country. Both of above thinkings come down in one continuous line and keep up with the times. From the proposal of building “Fuzhou on the sea” in Fuzhou to the proposal of building “a strong country on the sea” in the 18th National Congress of the CPC, Xi Jinping’s important discourse on building a powerful country in the ocean has gone through the process of deepening and sublimating from part to overall situation, from region to country, and from practical experience to theoretical construction. In the process, the strategic theory system of ocean power with Chinese characteristics has been gradually formed, and the “four beams and eight pillars” of ocean power strategy have been constructed.