To study the quality change of Chinese mitten crab during the frozen storage, sensory and physical and chemical indicators were used to judge the taste period of 180 days of gonad part and 240 days of meats. Fishy smell and rancidodor in the gonad part of crabs were too heavy after 180 days.Crabmeat was not accepted after 240 days because of the ammoniacal smell and fishy smell. The volatile odor substances of Eriocheir sinensis were extracted and detected by Solid-phase microextraction (SPME) and Gas Chromatography-mass Spectrometer (GC-MS) before and after freezing. The compounds were analyzed and selected by odor activity value (OAV). The results showed that the most important substances affecting the odor of Eriocheir sinensis after freezing were Benzaldehyde, Nonanal,2,6-Nonadienal, 1-Octen-3-ol, 2,4-Decadienal and Trimethylamine.