The invention relates to a biological fertilizer production technique for sufficiently utilizing arable layer nitrogen in order to eliminate nitrogen pollution, which relates to a production technique of a biological fertilizer, in particular to a production method of a biological fertilizer compounded with nitrobacteria, azotobacter and the like. The technique adopts the following technical processes: (1) using the method known by professionals in the industry to screen bacteria such as azotobacter, photosynthetic bacteria, algae, legume bacteria, nitrosobacteria, nitrobacteria, trichoderma, silicate bacteria, bacilli and denitrifying bacteriap; (2) carrying out experiments on the effects of the screened strains; (3) using the known method to respectively propagate each strain step by step according to the characteristics of the strain; (4) selecting different carrier materials for adsorption or drying according to the characteristics and purposes of the strains; (5) finally carrying out inspection and packaging. The invention is applicable to large-area mechanical spreading operation as well as manual spreading operation on crofts.