The invention discloses a preparation method of a bioorganic fertilizer. The method comprises the following steps: 1, preparing a substrate: naturally solarizing or drying pig dung, carrying out ultraviolet lamp irradiation disinfection for 30-120min, and overturning the pig dung 2-3 times in the irritation process to prepare the fermentation substrate; 2, carrying out two stage fermentation: sterilizing the fermentation substrate at 121DEG C for 20-30min, cooling the sterilized substrate to room temperature, adding water, and uniformly stirring to prepare a solid fermentation medium, inoculating a lactobacillus strain liquid, carrying out anaerobic fermentation for 48h, inoculating a Candida utilis strain liquid, introducing aseptic air, and carrying out aerobic fermentation for 48-72h to obtain a fermentation product; 4, drying: drying the fermentation product at 55-60DEG C; and 5, proportioning: adding a biological regulator to the dried fermentation product according to a weight ratio of 100:(0.2-1) in order to prepare the bioorganic fertilizer, wherein the biological regulator is photosynthetic bacteria and azotobacteria. The bioorganic fertilizer prepared in the invention can greatly improve the output per 666.7m<2> of land of crops.