The invention relates to a bacillus amyloliquefaciens insecticide-fertilizer for farm onsite fermentation, a preparation method and applications thereof. The insecticide-fertilizer comprises the following raw materials: bacillus amyloliquefaciens, colistin sulfate, natamycin, L-alanine, asparagine, yeast extract powder, peptone, disodium hydrogen phosphate, sodium chloride, glucose, fructose, and brown sugar. The colistin sulfate and natamycin in the insecticide-fertilizer can inhibit the growth of fungi (such as pathogenic fungi, yeast, etc.) and gram negative bacteria (such as colibacillus, salmonella, etc.) during the fermentation process. The spore germinator (alanine, fructose, and asparagine) can rapidly promote the germination of spores of bacillus amyloliquefaciens and improve the germination rate of spores. The provided insecticide-fertilizer can be applied to the onsite fermentation and propagation in a simple and crude farm. The required equipment is simple. The using amount of bacterium is little. The cost is low. The fermentation broth obtained through onsite fermentation has the advantages of high content and good activity. The insecticide-fertilizer can prevent disease, promote growth, and increase output and improve quality, and can be used as a microbial pesticide, and the effect is stable.