The invention discloses a Chinese medicinal herb plant protecting agent, which comprises the following raw materials: Euphorbia pekinensis, Rhizoma arisaematis, Pinellia ternate, Semen Strychni, Cortex Meliae, Fructus Toosendan, Litsea cubeba oil, castor oil, silicate, a surface active agent and a tackifier. A preparation method comprises the following steps: firstly decocting the Chinese medicinal herbs twice in water; merging filtrates and adding into an emulsifying reactor, then adding an emulsifying agent and uniformly mixing; then adding the Litsea cubeba oil and/or the castor oil for emulsifying; and finally adding a mixed seriflux of the tackifier and silicate, and fully mixing and homogenizing to obtain the product. The Chinese medicinal herb plant protecting agent is a novel pesticide preparation with the functions of killing insects, sterilizing and resisting viruses, can be singly used or/and used by being mixed with common pesticides, has effects of touch toxicity, intestine toxicity, nerve toxicity and sterilization on insects, keeps the advantages of low toxicity, high efficiency, easy degradation and no residual of Chinese medicinal herbs, has no drug resistance to insects or environmental pollution, has a good preventing and curing effect on horticultural plants and urban landscaping plants, and has good economic benefits, social benefits and environmental-protection benefits.