The invention discloses a method for detecting the number of live spores in bacillus subtilis original powder with one trillion live spores/per gram. The method comprises the steps that a sample to betested is dispersed with a diluent, the diluted sample is cultured on a nutrient agar culture medium, the number of bacterial colonies on a plate is counted, and the number of viable bacteria in thesample to be tested is calculated. According to the method, a phosphate buffer solution is adopted as the diluent, peptone is added at the same time, and therefore the sample can have a more stable dispersion environment; in addition, a pretreatment method of the sample and components of the nutrient agar culture medium are improved, and therefore the number of the spores of the high-content bacillus subtilis original powder is detected. The method can accurately detect the number of the live spores of a product, has the advantages of good detection repeatability, small deviation and the like,and is beneficial to reducing the detection frequency and the detection cost.