The invention discloses a liquid fertilizer capable of preventing soil-borne diseases. The liquid fertilizer is prepared from the following raw materials, by weight, 36-40 parts of biogas residue mud, 5-7 parts of sodium potassium tartrate tetrahydrate, 6-8 parts of citric acid, 40-50 parts of corn germ meal, 15-19 parts of urea, 55-65 parts of dry chicken manure, 120-140 parts of waste livestock and poultry feathers, 6-7 parts of copper sulphate, 4-6 parts of ferrous sulphate, 4-5 parts of GM microbial preparations and a proper amount of water. Biogas residue mud, chicken manure and the like are employed in the raw materials of the liquid fertilizer and contain a lot of microbes with various kinds, the GM microbial preparations are added to raise the beneficial bacterium content, thus the liquid fertilizer becomes a microbe resource base, the soil microbial community structure can be adjusted after drip irrigation and spraying of the liquid fertilizer, the soil microbial diversity is raised, the soil micro-ecological environment is improved, the survival scope of plant pathogens is narrowed, and therefore the purpose of preventing soil-borne diseases is achieved.