[Objective] The study was to screen the active part from roots of Macleaya cordata. [Method] Dipping method was used to study the contact activity of ethanol extract and 4 kinds of extracts by petroleum, ethyl acetate, n-butanol and water from the root of M. cordata on 2nd and 6th instars larvae of T. motlitorlin(L.). [Result] The corrected mortality rate of T. motlitorlin increased with the increase of extract concentration. When the concentration was 100 mg/ml, the contact activity of ethyl acetate extract against 2nd instar larvae of T. motlitorlin was the highest, the corrected mortality rate at 48 h reached 80.95%, and LC50 was 65.532 9 mg/ml. The overall performance of insecticidal activity was as follows: ethyl acetate layer > petroleum layer = n-butanol layer > total extracts (ethanol) > water layer. The contact toxicity of ethanol extract and petroleum extract against 6th instar larvae of T. motlitorlin was the highest, and the corrected mortality rate at 48 h reached 71.42% and 66.67%, LC50 were 83.899 8 and 86.687 7 mg/ml, respectively. The overall performance of insecticidal activity was as follows: total extracts (ethanol) > petroleum layer > ethyl acetate layer > n-butanol layer > water layer. [Conclusion] The insecticidal active components of M. cordata root were distributed within the polarity range of petroleum and ethyl acetate, and the part could be further separated and identified. [Objective] The study was to screen the active part from roots of Macleaya cordata. [Method] Dipping method was used to study the contact activity of ethanol extract and 4 kinds of extracts by petroleum, ethyl acetate, n-butanol and water from the root of M. cordata on 2nd and 6th instars larvae of T. motlitorlin (L.). [Result] The corrected mortality rate of T. motlitorlin increased with the increase of extract concentration. When the concentration was 100 mg / ml, the contact activity of ethyl acetate extract against 2nd instar larvae of T. motlitorlin was the highest, the corrected performance rate at 48 h reached 80.95%, and LC50 was 65.532 9 mg / ml. The overall performance of insecticidal activity was as follows: ethyl acetate layer The contact toxicity of ethanol extract and petroleum extract against 6th instar larvae of T. motlitorlin was the highest, and the corrected mortality rate at 48 h reached 71.42% a nd 66.67%, LC50 were 83.899 8 and 86.687 7 mg / ml, respectively. The overall performance of insecticidal activity was as follows: total extracts (ethanol)> petroleum layer> ethyl acetate layer> n-butanol layer> ] The insecticidal active components of M. cordata root were distributed within the polarity range of petroleum and ethyl acetate, and the part could be further separated and identified.