Objective: This study aimed to uncover antimicrobial activity and mechanism of LG-EO on Vibrio parahaemolyticus(VP). Methods: The antimicrobial activity and possible mechanism of LG-EO on VP were investigated through MIC(minimum inhibitory concentration)， time-kill assay， AKP (alkaline phosphatase) activity in supernatant， leakage of electrical conductivity(EC) and protein， cells morphology， membrane potential， respiratory chain dehydrogenase activity and intracellular DNA content and structure. Results: The MIC of LG-EO against three VP strains was about 80 μg/mL to 120 μg/mL， and the killing efficacy enhanced with increasing concentration at 80-280 μg/mL and extension of treated time. Treatment with 240 μg/mL LG-EO for 10 min resulted in no viable bacterial count of all three VP strains (detection limit 1lg CFU/mL). Treated with LG-EO above MIC， the integrity of the cell wall and membrane was disrupted， leading to a rise in AKP activity， protein content and conductivity in the supernatant and changes in cellular ultrastructure. In the VP strains treated LG-EO， cell membrane potential reduced， and activities of respiratory chain dehydrogenases and ATPases decreased， indicating the energy metabolism of VP was interrupted. Moreover， LG-EO could interact with bacterial DNA via intercalation， to disturb the normal cellular functions. Conclusion: LG-EO showed strong antimicrobial effect against VP by disrupting cell wall and membrane， interfering with cellular energy metabolism， causing DNA loss or denaturation. Thus， LG-EO is expected to be an alternative for novel multifunctional food additive with bacteriostatic action in aquatic food industries.