Abstract: To make clear whether the exogenous jasmonic acid (JA) could induce resistance of bean (Phaseolus vulgaris) plant and its effect on the enzyme activities in 2nd instar nymph of wes-tern flower thrips (Frankliniella occidentalis), the contents of nutrients and secondary metabolites were measured at 1, 5 and 10 days after spray of JA solution at the concentration of 1, 0.1, 0.01 or 0.001 mmol·L^-1 on bean leaves with healthy plants as control. Changes in enzyme activities were analyzed from 2nd instar nymphs of F. occidentalis that were inoculated on bean leaves treated as mentioned above. The results showed that there were not significant differences in protein contents of leaves at 1 day after treatment by different concentrations of JA with that of healthy bean plants, but the protein contents at 5 and 10 days after treatment were significantly lower than that of the control. The content of free amino acids in leaves at 1 day post treatment was significantly higher than that of the control and gradually decreased. After treatment of JA, the soluble sugar content was significantly lower than that of the control and decreased with the elevation of JA concentration and the prolongation of treatment time. The chlorophyll content in leaves at 1 day post JA treatment significantly decreased, but gradually rose with the increase of treatment time. The contents of tannins, flavones and phenols in leaves under different treatment time with various concentrations of JA were significantly higher than that of the control. The changes of biochemical substances of leaves damaged by thrips were similar to that of JA induction. After F. occidentalis feeding on the JA-treated bean lea-ves for 24 h, the activities of protective enzymes [i.e., superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD)] and detoxification enzymes [i.e., glutathione S-transferase (GST), carboxylesterase (CarE) and acetylcholine esterase (AchE)] in this insect were significantly higher than those feeding on healthy plants, but these enzymes’ activities changed to diffe-rent extent under different treatment time with various concentrations of JA. The changes of activities of enzymes in F. occidentalis feeding on leaves damaged by thrips were similar to that of feeding on the JA-treated leaves. These findings indicated that exogenous jasmonic acid could induce the resis-tance of bean plant, and F. occidentalis that had fed on bean leaves treated by JA generated anti-defended strategy to adapt to the change of host plants.