The invention discloses an application of a microbial fermentation preparation in biological prevention and treatment on tea scale insects. According to the invention, bacillus altitudinis, bacillus subtilis and bacillus licheniformis are fermented in a liquid fermentation broth added with tung seed cake, radix sophorae flavescentis, azadirachta indica and radix stemonae, a large number of plant secondary metabolites aiming at the scale insects are generated in the fermentation liquid, so that the scale insects are favorably killed, meanwhile, surface active substances such as lipopeptide substances and the like are generated, so that the plant resistance is enhanced, the non-specific resistance induced by secondary products is generated, and meanwhile, a large amount of plant growth regulating substances are also generated in fermentation liquor, so that the normal physiological activity of plants is facilitated; inorganic nutrition of plants is facilitated, and the plant tree vigor is enhanced. According to the method, the tea scale insects can be prevented and treated, the development of tea tree leaves can be promoted, the photosynthesis is enhanced, the quality of the leaves is improved, the improvement degree of the tea scale insects after spraying can exceed 70% or above, meanwhile, pesticide residues can be reduced, and the autumn tea picking safety is improved.