The invention discloses a method for preparing organic fertilizers from excrements of livestock and straws through anaerobic-anoxic and aerobiotic double-stage coupling and fermenting by a dry process. The method comprises the following steps: after pulverizing straws, adding water and moisturizing for 24 h; uniformly mixing the moisturized straws with the excrements of the livestock, adding a fermentation preparation, controlling the water content of a mixture to be 75%-80%, and carrying out dry-process anaerobic fermentation under the condition that the temperature is 30-40 DEG C to obtain clean energy and fermentation residues; and secondarily mixing the fermentation residues with the pulverized straws, covering the mixing with a film, stacking, turning the stack after the temperaturereaches 50-70 DEG C, and carrying out anoxic and aerobiotic fermentation to obtain the final product. The method is easy to operate and low in energy consumption, and secondary pollution does not exist; by two-time fermentation and the combined effects of anaerobic and aerobiotic different microbial communities, harmful substances in the fertilizers can be degraded or decomposed effectively, and synthesis of new nutritional ingredients is promoted; and the organic fertilizer obtained by the method becomes thoroughly decomposed, nutrients are abundant, and high-quality and effective resource utilization of wastes is realized.