The invention relates to a high-content dry Bacillus thuringiensis suspension and a preparation method thereof. The preparation method comprises the following steps: concentrating a Bacillus thuringiensis fermentation liquid to a solid content of 18-25%, uniformly mixing the obtained Bacillus thuringiensis fermentation liquid concentrate containing 50-80% of a solid material, 1.5-8% of a dispersant, 1-7% of a wetting agent and 5-15% of a disintegrating agent (and / or a filler) in a stirring tank, grinding and homogenizing by a sand mill to obtain a Bacillus thuringiensis slurry with a solid content of 24-35%, pressing the slurry into a spray granulator through a peristaltic pump, granulating at a hot wind inlet temperature of 150-180DEG C and a tail gas outlet temperature of 55-70DEG C to obtain a product with a water content of about 3%, screening to obtain the 50-80% dry Bacillus thuringiensis suspension. The product has a particle size of 30-100 meshes, is fluffy, has a suspension rate of above 88%, a dispersibility of above 80%, and is easy to disintegrate and disperse. A detection result shows that the virulence titer can reach above 64000IU / mg. The dry Bacillus thuringiensis suspension has the advantages of one-step granulation, low production cost, high suspension rate, good dispersibility, and no nozzle blocking, is an ideal biological medicine for preventing and treating resistant Lepidoptera pests, and is in favor of the food safety.