The invention belongs to the technical field of pesticide preparation research and development, and particularly relates to a green plant insecticide and a preparation method thereof. The green plant insecticide is prepared from the following raw materials by weight: 50-70 parts of hydnocarpus anthelmintica pierre, 20-40 parts of fructus carpesii, 25-35 parts of fructus podophylli, 15-25 parts of nux vomica, 20-35 parts of fructus kochiae, 25-35 parts of cortex phellodendri, 20-30 parts of plectranthus hadiensis var. tomentosus, 5-20 parts of menthol, 5-15 parts of climbing groundsel herb, 15-25 parts of portulaca oleracea, 15-25 parts of piper nigrum l, 15-30 parts of laurus nobilis, 15-30 parts of cyrtomium fortunei charcoal, and 15-25 parts of Baijiu. According to the present invention, the main components of the green plant insecticide are the natural traditional Chinese medicine raw materials, the ratio is reasonable, the raw materials provide the synergy effect, the residual time of the insecticide liquid in crops is short, and the insecticide can be automatically transformed into the fertilizer; and the green plant insecticide has characteristics of environmental protection, health, simple and convenient use, low toxicity, safety and low cost, provides good effects of insect disinfestation, pest expelling and sterilization for crops, can prevent and cure diseases, and has wide application range.