Abstract: Abstract: In order to extract insecticidal active ingredients from Aconitum flavum, new high efficiency active plant insecticide was researched. The total alkaloid was obtained with the extract process of degreasing, extraction and the technology of acid-extraction alkali precipitation by using the extraction fraction of 95% ethanol. The leaf disk method and dipping pest and leaf-disk method were used to test bioactivity of the total Alkaloid against Mythimna separata and Aphis sp.The results showed that the total Alkaloid had higher anti-feeding and stomach poisoning activity against 3rd instar larvae of Mythimna separata. The median anti-feedant concentration (AFC50) were 1.039 mg/mL at 24 h and 0.573 mg/mL at 48 h respectively, and the corrected mortality reached 96.6% at concentration of 10.0 mg/mLduring 72 h, the median-lethal concentration (LC50) was 1.939 mg/mL against 3rd instar larvae of Mythimna separata. The total alkaloid also showed greater contacting toxicity against Aphis sp., the corrected mortality reached 87.2% at 24 h and 96.5% at 48 h respectively at concentration of 10.0 mg/mL, and the median-lethal concentration (LC50) was 2.243 mg/mL at 24 h and 1.406 mg/mL at 48 h respectively. It was suggested that the total alkaloid of Aconitum flavum had higher biological activities against Mythimna separata and Aphis sp.