Abstract: The marine summer closed fishing season system is currently the most important marine fishery resource protection and management system, and it becomes an important measure to conserve marine biological resources, construct marine ecological civilization and promote the sustainable development of marine fisheries. Based on the comparison of the marine summer closed fishing season systems between the East China Sea and Zhejiang Province, this research discussed how to improve the marine summer closed fishing season system. Results show that the characteristics of the marine summer closed fishing season system of the East China Sea were extended closed fishing season, increased fishing gears and methods for and refined closed fishing area. While the main characteristics of the marine summer closed fishing season system in Zhejiang Province were the summer closed fishing season of “set-net” and “stow net”, closed protected fishing area, closed fishing for protecting specific biological resources, and included fishery support vessels in the marine summer closed fishing season system. Compared with the marine summer closed fishing system of the East China Sea, the practice in Zhejiang have more advantages, providing a useful inspiration for constructing protected marine organism areas, extending the closed fishing season and managing fishery support vessels. Lastly, on the basis of the periodical closed fishing season system, this paper also provides some policy recommendations of establishing diversified closed fishing season to improve the marine summer closed fishing system and sustainable development of inshore fishery, including closed fishing in marine protected areas, closed fishing season for special fish resources, and temporary closed fishing season.