The invention discloses a biological fertilizer for reducing cadmium content in tobacco, a preparation method and an application thereof. The biological fertilizer comprises the following components in parts by weight: 30-40 parts of wheat bran, 30-40 parts of orange peel, 20-30 parts of potassium metasilicate, 10-20 parts of meerschaum, and 0.2 parts of microbe bacterial strain. The microbe bacterial strain comprises phosphate solubilizing bacteria, potassium releasing bacteria, azotobacteria and bacillus. The biological fertilizer has the beneficial effects that the preparation method is simple, the components are easily obtained, the practicability is strong, and the biological fertilizer is convenient for popularization in agriculture production. The operation mode is simple, the available cadmium in acidic soil and cadmium content in tobacco leaf can be obviously reduced through fertilizing, secondary pollution is not generated on the soil, and output and quality of the tobacco leaf are increased.