In order to investigate the quorum-sensing inhibition of 2-methyl-2-pentenoic acid and its quorum-sensing effect on Pseudomonas fragi by using the reporter strain Chromobacterium violaceum 026 (CV026). The inhibition effect of 2-methyl-2-pentenoic acid on the population induction of P. fragi was analyzed by bacterial apoptosis rate， gas chromatography-mass spectrometry analysis， biofilm inhibition effect， the amount of extracellular polymer formed， bacterial swarming and swimming. It was demonstrated that the minimum inhibitory concentration of 2-methyl-2-pentenoic acid was 0.5 mg/mL， and 2-methyl-2-pentenoic acid could reduce the ability of CV026 to produce purple bacteriocin at sub-inhibitory concentration and did not affect the apoptosis. The population-sensing signal molecules C8-HSL and C10-HSL produced by P. fragi were detected quantitatively by gas chromatography-mass spectrometry， and 2-methyl-2-pentenoic acid had an inhibitory effect on the secretion of the produced signal molecules. The biofilm formation of P. fragi by subinhibitory concentration 2-methyl-2-pentenoic acid was 21.06%， and the inhibition of bacterial swarming and swimming was reduced by 34.06% and 75.02%， respectively， in a concentration-dependent manner. In conclusion， 2-methyl-2-pentenoic acid had good population induction inhibitory property and could be used as a population induction inhibitor in aquatic preservation.