In view of prawn melanosis, sulfite abuse and short shelf-life, a complex preservative (a mixture of chitosan and anti-melanosis material) without sulfite was developed. The effects of Trachypenaeus curvirostris preservation and anti-melanosis were verified. According to the results of orthogonal experiment L9 (34), the optimum composition of chitosan 0.5 g/L, phytic acid 0.5 g/L, EDTA 0.5 g/L and 4-HR 0.01 g/L was determined. Results showed that complex preservative treatment slowed down the increase of aerobic plate count (APC) and total volatile basic nitrogen (TVB-N) of Trachypenaeus curvirostris significantly, and melanosis was inhibited effectively during storage at (5±1)℃. Shelf-life of Trachypenaeus curvirostris treated by the complex preservative doubled almost. The complex preservative has great application prospects, and the cost of processing one kilogram prawns was only 0.22 Yuan.