In order to study the effect of different fermentation methods on the quality and volatile substances of mussel cooking liquor. The mussel cooking liquor was fermented by lactic acid bacteria alone， yeast alone and lactic acid bacteria/yeast mixture. Effects of different fermentation methods on the qualities of mussel cooking liquor were studied through the changes of pH value， glucose， total soluble nitrogen (TSN)， amino acid nitrogen (AAN)， free amino acids (FAA) and organic acids (citric acid， malic acid， lactic acid and succinic acid) content. Moreover， the changes of volatile substances in mussel cooking liquor after fermentation were analyzed by gas chromatography mass spectrometry (GC-MS)， and the effects of different fermentation methods on the volatile substances of mussel cooking liquor were studied. The results showed that the mixed fermentation group had the lowest pH (4.6)， glucose content (6.36 mg/mL) and trimethylamine content (22.15 μg/mL)， and the highest TSN content (18.68 μg/mL)， FAA content (24.21 mg/mL) and AAN content (77.39 mg/mL)， indicating that the mixed fermentation had the best quality. In addition， mixed fermentation could produce more alcohols and esters， and reduce unpleasant flavor substances such as unsaturated aldehydes and amines in the sample. Lactic acid bacteria/yeast mixed fermentation could give samples better quality and flavor， suitable for the fermentation of mussel cooking liquid. This paper aimed to study the effects of different fermentation methods on the quality and volatile substances of mussel cooking liquor， and provide reference for the valorization of mussel cooking liquor.