NOVELTY - Producing bio-organic fertilizer involves: a) taking sludge having water content of 80% and crop straw powder in urban sewage treatment plant, adding 0.5 wt.% straw rotten agent and mixing, controlling water content in fermentation tank, controlling temperature at 40-70 degrees C, fermenting for 10-15 days, reducing temperature at 20-30 degrees C, controlling water at 20-30% and fermenting into powder; b) crushing, sieving, and stirring fermenting sludge and straw powder in disc granulator to particles; c) drying particle; and d) spraying phosphorus, potassium, nitrogen-fixing bacteria to particles.    USE - For producing bio-organic fertilizer using urban domestic sewage factory sludge and crop straw (claimed).    ADVANTAGE - The biological organic fertilizer produced by the method can not only effectively improve the soil structure, soil fertility, and soil environment, at the same time, can obviously improve the quality of the crop and produce the non-polluted green agricultural products; and can be widely applied to all kinds of agricultural and forest and economic crops. The production method solves the problem that the existing technology has dirty environment of straw secondary pollution and wastes a large amount of organic fertilizer source.    DETAILED DESCRIPTION - Producing bio-organic fertilizer using urban domestic sewage factory sludge and crop straw, involves: a) fermentation tank fermentation: taking the sludge having water content of 80% and crop straw powder in the urban sewage treatment plant equipped with fermentation culture medium, and adding 0.5 wt.% straw rotten agent as ferment culture medium, and mixing uniformly, controlling water content at 50%, in fermentation tank fermentation aerobic fermentation workshop day mechanical overturning time, controlling the temperature at 40-70 degrees C, fermenting for 10-15 days, reducing the temperature at 20-30 degrees C, controlling water content at 20-30% and fermenting the fermentation material into powder, after completion of fermentation, when there is no smell; b) ball granulation: crushing, sieving, and then stirring the fermenting sludge and straw powder in the disc granulator to particles; c) drying: drying the particles at 250 degrees C drying; d) spraying phosphorus, potassium, nitrogen-fixing bacteria strain to particles on drying to obtain the bio-organic fertilizer.