Abstract: On the base of the research of single biological preservative, the orthogonal experiment was made to investigate the fresh-keeping effect of complex biological preservatives (a miture of lysozyme, nisin and chitosan) in the preservation of pomfret under the cold storage. The total bacterial count, TVB-N were used to evaluate its quality. According to the results of orthogonal experiment L9 (33) , the best concentrations of lysozyme, chitosan, and Nisin were as follows 0.4, 5, 0.4g/L. The sensory scores, total bacterial count, TVB-N and TBA of pomfret treated by the complex biological preservatives were better than uncoated one. The first grade freshness of pomfret treated by the complex biological preservatives could be extended 2 ³ days, and the two grade freshness could be extended 6⁷ days.