Abstract: The antibacterial activity and mechanism of limonene against Pseudomonas aeruginosa were evaluated. The results showed that MIC of limonene on P. aeruginosa was 10 mL/L. Limonene inhibited the normal growth and proliferation of P. aeruginosa by measuring the bacterial growth curve. Limonene could destroy the normal morphology of cell, increase the relative conductivity of bacteria and the permeability of the cell membrane.Further,limonene reduced the membrane potential, interfered with normal metabolic activity of cell. By scanning electron microscopy, limonene destroyed cell membrane and inhibited the growth of P. aeruginosa,resulting in bacterial death.Limonene could change the permeability of the cell membrane of P. aeruginosa,destroy the normal cell morphology and integrity,thus effectively inhibit the normal growth.