The aim of this study was to investigate the mechanism of high hydrostatic pressure （HHP） on the dominant spoilage bacteria in aquatic products-Shewanella putrefaciens and to understand the changes in bacterial cell damage and death. The treatment conditions were set at 200， 300 MPa and 400 MPa for 9 min respectively； samples treated by 0.1 MPa were used as controlled one. Different parameters， such as survival rate， bacterial growth curve， electrical conductivity， propidium iodide（PI） intake， the content of nucleic acid and protein， enzymatic activity， were analyzed respectively. Scanning electron microscopy （SEM） can be used to observe the damage of Shewanella putrefaciens under different HHP conditions. The results showed that when compared with CK group， the growth of Shewanella putrefaciens could be greatly inhibited after different HHP treatment and the logarithmic phase of bacteria can be delayed. 300 MPa and 400 MPa for 9 min treatments could kill all of the bacteria. Electrical conductivity and PI intake were positive correlation with the pressure， but the activity of Na+/K+-ATPase in bacterial cell membrane was significantly decreased. The results of SEM observation showed that the level of deformation and cell damage were related to the increase of pressure. HHP treatment can inhibit the growth of bacteria， destroy its structure， inactive the enzymatic activity， which led to the death of bacteria.