The invention discloses a biopesticide missible oil preparation for preventing vegetable pest plutella xylostella and belongs to mixed biopesticide. Mixed biopesticide missible oil preparation for preventing plutella xylostella aims to be high in penetrability, good in pest killing effect, durable in pesticide effect and low in cost and is mixed by, by weight, 0.1-30% of macleaya cordata ethanol extract, 0.1-10% of azadirachtin, 1-40% of surfactant, 0.2-20% of cosolvent, 1-2.5% of sun-screening agent, 0.1-2% of corrosion remover, 0.1-30% of stabilizer, 0.5-10% of synergist, 5-40% of organic solvent, 0.1-24% of penetrant and 0.01-0.5% of pH value modifier, and the sum of proportions of all the components is 100%. According to the biopesticide missible oil preparation for preventing vegetable pest plutella xylostella, the synergism of the macleaya cordata ethanol extract and the azadirachtin is used for overcoming the pesticide resistance of pests, the preventing effect can be improved, the insecticidal spectrum is expanded, and the defect of a single kind of pesticide is overcome. The biopesticide can prevent vegetable pest plutella xylostella.