The invention discloses an environment-friendly insecticide and a preparation method and application thereof. The insecticide is prepared from, by weight, 30-50 parts of the root of Chinese pulsatilla, 80-100 parts of pyrola, 10-20 parts of thunder god vine, 10-20 parts of radix euphorbiae lantu, 25-40 parts of radix arnebiae seu lithospermi, 10-20 parts of eupatorium, 5-10 parts of polysorbate, 5-10 parts of dimethyl sulfoxide, 2-5 parts of turpentine, 2-5 parts of ethyl alcohol, 1-2 parts of sorbic acid and 100-200 parts of softened water. The insecticide is free of pollution, safe and obvious in deinsectization effect.