[Aim] To explore the effect of five insecticides on toxicity and activities of protective and detoxifying enzymes of Frankliniella occidentalis and closely-related species F. intonsa,which provides basic information for further studies on pest resistance management.[Method] The toxicity of five insecticides to F. occidentalis and F. intonsa was determined using the dipping method, and the activities of protective and detoxifying enzymes were measured after treatment with sublethal concentrations (LC₂₅) of each insecticide.[Result] The toxicities of the five insecticides to F. occidentalis and F. intonsa were spinetoram>emamectin benzoate>avermectin>imidacloprid>thiamethoxam. The LC₅₀ values to spinetoram in F. occidentalis and F. intonsa were 0.28 and 0.03 mg·L^-1, respectively. The activities of protective and detoxifying enzymes in F. occidentalis and F. intonsa were induced after LC₂₅treament. Avermectin had the strongest induction effect on superoxide dismutase (SOD) activity of F. occidentalis at 326.40 U·mg^-1, which was 9.37 times that of the control. Spinetoram had the strongest induction effect on SOD activity of F. intonsa at 245.35 U·mg^-1, which was 9.32 times that of the control. Imidacloprid had the strongest induction effect on peroxidase (POD) in both F. occidentalis (298.67 U·mg^-1) and F. intonsa (246.79 U·mg^-1), which were 37.10 and 20.57 times those of the control, respectively. Avermectin had the strongest induction effect on catalase (CAT) and carboxylesterase (CarE) of both thrips species, at 298.67, and 246.79 U·mg^-1 (CAT activity) and 12.53, and 11.99 U·mg^-1 (CarE activity), respectively. Spinetoram had the strongest induction effect on glutathione S-transferase (GST) at 77527.59, 66927.39 U·mg ^-1(GST activity) and also for acetylcholine esterase (AChE), at 2.34, and 2.22 U·mg^-1 (AChE activity), respectively.[Conclusion] Among the five insecticides tested, spinetoram showed the strongest toxicity against both thrips. The detoxification ability of F. occidentalis was better than that of F. intonsa.