This paper constructs an evaluation index system for the high-quality development of the marine economy based on the five dimensions of the new development paradigm. It employs entropy method, kernel density analysis, and Dagum Gini coefficient method to analyze the high-quality development level of China's marine economy and its spatial-temporal evolution from 2013 to 2022. The findings reveal that: (1) The comprehensive index for the high-quality development of China's marine economy exhibits an overall fluctuating upward trend; (2) The high-quality development levels of the marine economy in the eastern and southern marine economic circles are both above the national average, while that in the northern marine economic circle is below the national average; (3) The focus of high-quality development in China's marine economy is shifting towards economically developed regions along the southeast coast, demonstrating a trend of "higher in the south and lower in the north." Moreover, the gap in high-quality development of the marine economy among the three major marine economic circles is gradually narrowing, and the high-quality development of regional marine economies tends to become more coordinated.