The invention provides a pure natural vegetable insecticide and a preparation method of the pure natural vegetable insecticide. The pure natural vegetable insecticide comprises the following ingredients by weight: 20-30 parts of black false hellebore, 8-13 parts of radix sophorae flavescentis, 12-15 parts of eucalyptus leaf, 2-5 parts of tobacco leaf, 1-3 parts of radix stemonae, 30-40 parts of rose willow floral leaf, 1-2 parts of surfactant, 0.4-0.8 part of sulfated castor oil, 0.00001-0.00002 part of microcrystalline cellulose, 0.2-0.4 part of passion fruit, and 10-15 parts of bitter gourd. The pure natural vegetable insecticide has the beneficial effects that: the pure natural vegetable insecticide has a good insecticidal effect, and gives out a smell hated by the insect to play a role in preventing; the pure natural vegetable insecticide acts for a long period of time, then the planting cost is reduced; the pure natural vegetable insecticide promotes the growth of plants, shortens the growing period of the plants, increases the volume of vegetables, the fruiting rate of a fruit tree and the yield; no pollution or residue is caused, no drug resistance is produced, and the use amount of the pure natural vegetable insecticide is not increased even for long term use.