NOVELTY - Preparing urban waste into organic fertilizer through near-critical water technology comprises sorting waste; treating organic matter raw material; pre-treating in pyrolysis; pyrolyzating; and adjusting the pH value of the pyrolytic raw material.    USE - The method is used for preparing urban waste into organic fertilizer through near-critical water technology (claimed).    ADVANTAGE - In the method above, oxygen-enriched air is used as the oxidant so that the raw material is fully oxidized in pyrolysis and completely decomposed. The method is environment-friendly and secondary pollution is avoided. Enough pyrolysis time will completely kill germs, viruses and parasite, thus making sure of the utilization safety of the fertilizer. The heavy metal removing treating technology is used for preventing the heavy metal in the product from harm to soil and crops. The reasonable pyrolysis temperature fully decomposes the components in the organic matter. Resource utilization is maximized. The production cost is low. The method makes sure that waste is reduced.    DETAILED DESCRIPTION - Preparing urban waste into organic fertilizer through near-critical water technology comprises sorting and pyrolyzating, where the method comprises (a) sorting waste: manually sorting the urban waste, selecting the large matters, crushing, sieving, separating in gravity, selecting with wind, selecting magnetically, sorting through grain diameter so as to divide the urban waste into the organic matter, inorganic matter, combustible matter, ferromagnetic matter and metal and taking the organic matter for spare use; (b) treating organic matter raw material: crushing and sieving the sorted organic matters, conveying the raw material whose grain diameter is not greater than 90 mm to an organic matter storing cabin, magnetically sorting during raw material treatment and removing the ferromagnetic material; (c) pre-treating in pyrolysis: sending the organic matter raw material into a pyrolysis kettle to reach 80% of the volume of the pyrolysis kettle, adding the oxidant that is pre-heated to 20-30 degrees C at the same time, where the oxidant is the mixed gas of air whose oxygen content is 10-25% and oxygen, adding overheat water to immerge the surface of the raw material, where the temperature of the overheat water is 80-90 degrees C; adding magnesium oxide whose concentration is 5-10%, where the weight ratio of magnesium oxide to the organic matter raw material is 100:3-5; (d) pyrolyzating: continuing to add oxidant to the pyrolysis kettle, stopping adding oxidant when the pressure in it reaches 0.1-0.2 Mpa, heating the pyrolysis kettle, heating from a normal temperature to 150 degrees C for about 10 minutes in a low temperature stage, heating from 150-200 degrees C for about 15 minutes in a medium temperature stage, insulating for 10 minutes, heating from 200-300 degrees C for about 10 minutes in a high temperature stage, insulating for 10 minutes, controlling the pressure in the kettle at 0.6-1.25 Mpa in the whole pyrolysis process, reacting for 50-70 minutes, stopping releasing pressure when the pressure in the pyrolysis kettle is released to 0.2 Mpa, discharging the water steam and pyrolysis liquid in the pyrolysis kettle, adding hot air at lower than 100 degrees C to dry the raw material until its water content is not greater than 30%, preserving the pressure at 0.3-0.4 Mpa, instantly opening the material discharge valve of the pyrolysis kettle, spraying the raw material in the kettle to a spraying cabin to finish the pyrolysis process, removing the impurity and the heavy metal in the pyrolysis liquid to use the pyrolysis liquid as the water for pyrolysis in circulation; and (e) adjusting the pH value of the pyrolytic raw material to 6.5-7.5, crushing and sorting through grain diameter and taking the grains whose phi is not greater than 6 mm as the organic fertilizer.