Abstract: The tests on insecticidal activities of the non-alkaloid extracts from Tripterygium wilfordii Hook.f.against Plutella xylostella L. were conducted. The results show that the non-alkaloid extracts from T. wilfordii has a strong antifeedance toxicity and growth inhibiting activities. The medium antifeedance concentration (AFC₅₀) of the non-alkaloid extracts against the 2^nd instar larva of P. xylosella are 34.89mg/L and 42.33mg/L in the choice and no-choice tests, respectively. The medium lethal concentration (LC₅₀) against the 2^nd instar of P. xylosella is 49.86mg/L. The non-alkaloid extracts also shows a strong growth inhibiting activity to the larva of P. xylosella. But the effect of the non-alkaloid extracts on the eggs of L.xylosella is not obvious. The egg hatchability and survival rate of the newly-hatched larva of P. xylosella treated with 400mg/L of the non-alkaloid extracts are 53.48% and 46%, respectively.