In this paper,vinegar secondary precipitate was prepared by centrifugation coupling with vacuum freeze-drying.By comparison with the supernatant of vinegar,the proximate indices and characteristics of proteins of the vinegar secondary precipitate were analyzed using SDS-PAGE and HPLC.Results showed that vinegar secondary precipitate was mainly composed of proteins and small quantity of NaCl and free amino acids.The proteins in vinegar secondary precipitate were existed in the forms of high molecular weight proteins or their polymers(> 116 kDa).Its amino acid composition was obviously different from that of the supernatant,and its average hydrophobicity(HΦ avg) was obviously higher than that of the supernatant.In conclusion,the amino acid composition and higher HΦ avg of proteins in vinegar secondary precipitate were important contributors for the formation of vinegar secondary precipitate.