Vibrio parahaemolyticus is a foodborne pathogen of high risk in marine foods. In this study， an antimicrobial peptide designated FAH34(amino acid sequence: KTISFILK) was identified from distiller's grains Larimichthys crocea， and its thermal stability， antibacterial activity， and mechanism of action against V. parahaemolyticus explored. Peptide FAH34 had a minimum inhibitory concentration (MIC) of 7.80 μg/mL， while time-kill analysis showed that bacteria numbers decreased time-dependently from 5.06 lg(CFU/mL) to 0 lg(CFU/mL) within 3 h upon treatment with FAH34. Transmission electron microscopy examination revealed that FAH34 caused the destruction of bacteria membranes resulting in the leakage of bacterial contents. Besides， heat treatment (80 ℃ for 30 min or 121 ℃ for 15 min) of FAH34 did not significantly affect its antibacterial activity. Moreover， peptide FAH34 (with and without heat treatment) did not significantly affect the viability of LO₂ cells. Additionally， FAH34 could reduce bacteria (V. parahaemolyticus) counts to 0-0.40 lg (CFU/mL) in fish and marinade. These findings indicate that peptide FAH34 can be used as a biological preservative against V. parahaemolyticus in fermented foods or thermally processed foods.