NOVELTY - Preparing water retention of nitrogen fixation co-microbial fertilizer involves preparing fermentation liquid: drying wheat straw, then crushing into straw with a crusher, adding to the fermentation tank in, then add into fermentation tank in soybean meal, wheat bran and water at 100 degrees C, stirring uniformly, reducing temperature to 30 degrees C, adding composite liquid, stirring, fermenting for 48 hours, to obtain fermentation liquid; preparing stock solution; preparing composite microbial fertilizer by mixing coal powder, mono-ammonium phosphate, potassium chloride, urea, and water uniformly.    USE - For preparing water retention of nitrogen fixation co-microbial fertilizer.    ADVANTAGE - The method effectively utilizes manure crop waste, and the use of microbial fermentation technology to improve the soil structure, controls nutrient loss during use, making fertilizer more lasting, with farmers, provides high and stable yield of crops.    DETAILED DESCRIPTION - Preparing water retention of nitrogen fixation co-microbial fertilizer involves preparing fermentation liquid: drying the wheat straw, then crushing into straw with a crusher, adding to the fermentation tank, then adding into fermentation tank in soybean meal, wheat bran and water at 100 degrees C, stirring uniformly, reducing temperature to 30 degrees C, adding composite a liquid, 100-150 revolution/minute, stirring, fermenting for 48 hours, obtain the fermentation liquid, where the straw powder, soybean meal, bran, water and mass ratio of mix a liquid is 10:3:3:50:1, 2) preparing composite organic matter material liquid: adding grass peat, humic acid, zeolite powder and water according to mass ratio of 2:2:1:10, stirring tank in 300-400 turns/minutes, stir for 30 minutes, then entering into reaction tank, to 10 degrees C/minute, heating at 100 degrees C, heat preservation reaction for 5-10 minutes, then cooling to room temperature, standing for 12-24 hours, a composite organic liquid; step 3) preparing composite microbial fertilizer according to the coal powder, mono-ammonium phosphate, potassium chloride, urea, composite organic matter material liquid and water, stirring uniformly, adding to double-screw extruding in pelletizer, exit is set with cutting machine, the strip-shaped fertilizer taking off, finally spray the fermentation liquid, stirring uniformly, low temperature drying a water content is 1-2%, packing to obtain co-microbial fertilizer product.