The article explained that inhibitory components from Myriophyllum spicatum with the ultrasonic-cellulase method and water extraction method caused inhibition of M.aeruginosa. Based on one-way and orthogonal test, and regarding growth inhibition rate of extraction on M. aeruginosa as index of evaluation, an optimal extraction process of Myriophyllum spicatum was obtained as follows: enzymatic hydrolysis time was 4 h, pH was 3.0, optimal temperature was 30 ℃, cellulase dosage(mass of cellulase to Myriophyllum spicatum powder) was 21%, ultrasonic power was 120 W and ultrasonic time was 1h. The inhibition rate of extraction obtained with water extraction method and ultrasonic-cellulase method indicated that the latter showed better effect and had obvious difference with the water extraction (P<0.05). With the increasing of reaction time, the growth inhibition rate of the ultrasonic-cellulase extraction on M. aeruginosa continued to decrease, which was 271.74% at concentration of 40 g/L and reaction time for 24 h and the inhibition rate was more than 20% by the reaction time for 13d with the obvious difference with the other concentration groups (P<0.05).