NOVELTY - Organic solid waste aerobic composting, deodorizing and nitrogen preserving device, is operated by maintaining central temperature of piled material in primary fermentation reaction channel at 55-65 degrees C, starting mechanical pile overturning machine and waste liquid backward spraying system, pumping smelly gas produced by the piled material to gas inlet of biological trickling filter tower for degradation and purification, recycling spraying liquid, and mixing with percolate produced during aerobic composting process.    USE - Operation of organic solid waste aerobic composting, deodorizing and nitrogen preserving device for production of mixed fertilizer composition containing ammonium nitrate-calcium carbonate (claimed) for crop.    ADVANTAGE - The operation can reduce the loss of ammonia and nitrogen during composting process to 95%; is simple; and has good deodorization effect by using biological trickling filter tower, and good effect in thoroughly decomposing compost and in effectively controlling volatilization of ammonia and nitrogen. The organic-inorganic mixed fertilizer composition is easily absorbed by crop.    DETAILED DESCRIPTION - Operation of organic solid waste aerobic composting, deodorizing and nitrogen preserving device, comprises:    (A) maintaining central temperature of piled material in primary fermentation reaction channel at 55-65 degrees C by discontinuously extracting air using a high-pressure centrifugal exhauster, and starting mechanical pile overturning machine and waste liquid backward spraying system for overturning pile and backward spraying when central temperature of piled material is higher than 70 degrees C;    (B) pumping smelly gas produced by the piled material in primary fermentation reaction channel to gas inlet of biological trickling filter tower using the high-pressure centrifugal exhauster, to degrade and purify the smelly gas by microbe at a filling layer;    (C) increasing use amount of spraying liquid in biological trickling filter tower when temperature of inlet air is higher than 50 degrees C, and maintaining pH of spraying liquid in biological trickling filter tower at 6.5-7.5; and    (D) recycling spraying liquid rich in nitrate ion (NO3-) for several times, entering to water quality adjusting pond of waste liquid backward spraying system, mixing with percolate produced during aerobic composting process, adding saturated calcium hydroxide (Ca(OH)2) solution for adjusting, and backward spraying the mixed solution.