The invention discloses a high-efficiency multi-bacterial activity biogas residue biofertilizer and a preparation method thereof, and relates to the field of farm fertilizers. The biofertilizer is prepared by mixing and granulating 44 to 54 weight parts of biogas residue, 10 to 15 weight parts of potassium chloride, 10 to 15 weight parts of humic acid, 0.4 to 0.6 part of secondary and micro-element, 0.4 to 0.6 weight part of microbe, 5 to 10 weight parts of urea, 10 to 15 weight parts of monoammonium phosphate and 5 to 10 weight parts of ammonium chloride. The high-efficiency multi-bacterial activity biogas residue biofertilizer has the characteristics of better multiple bacteria co-existing environment, stronger bioactivity, higher fertilizer efficiency, complete organic matters, effective micropopulations and chemical nutrients, controlled-release effect and the like, can be used as a fertilizer for rice, also can be used as a fertilizer for Upland food crops, vegetables, melons and fruits and fruit trees, and can improve the fertility of land and the utilization rate of the fertilizer, improve the quality of agricultural products, enhance plant diseases and insect pest resistance and drought resistance, purify and repair soil and the like after being applied.