Seafood has important health benefits, and the growing demand for aquatic products has stimulated rapid trade development. Using 2000–2018 data from the UN Comtrade Database, this study first introduced the export scale, product structure, and market distribution of China’s aquatic products. Then, using an extended constant market share model, we investigated the factors affecting fluctuations in China’s aquatic product exports to the USA, Japan, South Korea, the Association of Southeast Asian Nations (ASEAN), and the European Union (EU). Import demand was found to be the most important factor affecting China’s aquatic product exports. Moreover, China’s export structure and market distribution for aquatic products have become increasingly consistent with global demand. In recent years, China’s aquatic product competitiveness has declined while its market destinations have diversified. Regarding China’s aquatic product types, the main focus has been on labor- and resource-intensive products with low competitiveness. More recently, however, China’s competitiveness of product types 0371 and 0372 (Standard International Trade Classification) has been improving in the world market. To further develop China’s aquatic product exports, policy should aim to maintain the fisheries ecosystem, encourage seafood operators to adopt good practices, increase investment in science and technology, overcome technical barriers to trade, strengthen research on the needs, preferences, and requirements of major importing countries, expand domestic demand, and strengthen international cooperation.