The microwave-assisted extraction of ricinine from castor meal was studied by single factor experiment and response surface methodology.The antibacterial activity of ricinine was also investigated by filter paper method.The optimum extraction parameters of ricinine were as follows:microwave power 408.01 W,extraction time 5.21 min and ratio of liquid to solid 12(mL∶ g).Under the above conditions,the predicated extraction rate was 50.74 %,and the actual extraction rate was 50.81 %.The relative deviation was 0.14 %.There was no significant difference between predictive value and actual value.The antibacterial activity of ricinine showed that ricinine had inhibition capacity to all tested strains,and the inhibition order was:Escherichia coli > Bacillus amyloliquefaciens > Staphyloccus aureus.