The invention provides a botanical insecticide as well as a preparation method and application thereof, and belongs to the technical field of insecticides. The botanical insecticide comprises effective components and an auxiliary agent, the effective components comprise the following raw materials in parts by weight: 5-10 parts of toosendanin, 2-4 parts of
crotonic acid and 4-8 parts of a Chinese
tallow tree extract; the auxiliary agent is prepared from the following raw materials in parts by weight: 40 to 50 parts of
methyl oleate, 2 to 5 parts of
pesticide emulsifier 500 #, 5 to 10 parts of organic
silicon surfactant L-775 and 5 to 10 parts of EL-90. According to the invention, the botanical insecticidal components including toosendanin,
crotonic acid and
sapium sebiferum extract are compounded with
methyl oleate,
pesticide emulsifier 500 and organic
silicon surfactants L-77 and EL-90, so that the synergistic effect is obvious, and the broad-spectrum insecticidal effect is achieved. The insecticide is non-toxic to human and
livestock, is environment-friendly, and is beneficial to improving the quality of agricultural products.