Salt content is essential for the quality of aquatic products, especially for the water-holding capacity and textural properties of salted products and the gel properties of surimi-based products. However, the salt content in traditional aquatic products is generally too high to meet consumers’ demand for healthy convenience foods with low salt content. Reducing the salt content will decrease the storage stability, eating quality and processing properties of aquatic products. Therefore, reducing the salt content without sacrificing the quality is an important issue faced by the aquatic product processing industry. The premise and basis of effectively controlling the quality of aquatic products with low salt content is to clarify the effect and mechanism of NaCl on the quality of aquatic products. In the present paper, we review the role of NaCl in the processing and storage of aquatic products and the latest progress of salt reduction technologies from the aspects of NaCl substitution, novel salt reduction technologies, and sodium release/perception enhancement technologies, and we discuss the problems with the processing of salt-reduced aquatic products. The present article may provide valuable information for high-quality processing of lightly salted aquatic products.