NOVELTY - A natural gas is produced by subjecting the rice hull to pulse aeration to obtain aerated material having pH value of 3.5-5.5; extracting the aerated material with water, and centrifuging and separating formed extract to obtain solid-phase and light-phase materials; fermenting the liquid-phase material to produce marsh gas; desulfurizing marsh gas by using a natural gas desulfurizing apparatus; and compressing the desulfurized material, liquefying carbon dioxide to obtain rice hull natural gas, and separating out the natural gas.    USE - Method for producing natural gas from rice hull (claimed).    ADVANTAGE - The method economically and effectively utilizes rice hull which is abundant in source; requires less labor and management cost; produces biological natural gas which has higher heat transformation than biomass such as cellulosic ethanol, biomass methanol, biological oil, biological pyrolytic oil, hydrogen; and utilizes closed internal circulating system, which is environmental-friendly with high economical benefit.    DETAILED DESCRIPTION - Production of natural gas comprises providing rice hulls having water content of 10-15%; subjecting the rice hull to pulse aeration at aeration pressure of 1.5-4 MPa for 5-180 sec, and controlling the aeration pulse for 0.006-0.09 seconds to obtain aerated material having pH value of 3.5-5.5; adding water to the aerated material at weight ratio of 5:1, stirring and extracting at normal temperature for 10 minutes to obtain an extract, and centrifuging and separating the extract to obtain solid-phase and light-phase materials; fermenting the liquid-phase material to produce marsh gas; desulfurizing marsh gas by using a natural gas desulfurizing apparatus; and compressing the desulfurized material in a medium compressor, liquefying carbon dioxide at 7-8 MPa such that the carbon dioxide separate from the methane and rice hull natural gas is obtained, and separating out the natural gas. The obtained natural gas meets the index of GB 178201999 natural gas technology. The step of fermenting the liquid-phase material comprises:    (A) conditioning pH value of the liquid-phase material to 7, pumping through a filter into a methane-phase fermenting pot and adding active marsh mud (10-20 wt.% of liquid-phase material) for anaerobic fermentation, controlling pH at 6.5-7.5 and temperature at 30-40 degrees C for 12 hours to produce marsh gas comprising methane (70-75), carbon dioxide (18-20), and hydrogen sulfide and other impurities (balance), and to obtain waste fermenting liquid of methane phase;    (B) adding obtained solid-phase material into acid-phase fermenting pot, adding water into the pot at solid-phase material:water weight ratio of 1:3, adding active marsh mud (10 wt.% of solid-phase material), uniformly stirring to ferment and produce an acid, controlling pH value at 4-5.5 and temperature at 30-35 degrees C in the acid-phase fermenting pot to obtain acid liquid and waste slag; and    (C) pumping the acid liquid into methane-phase fermenting pot from acid producing fermenting pot when pH value of the methane-phase fermenting pot is greater than 7.5, reducing the pH value to 6.5, supplementing the waste fermenting liquid of methane phase when the pH value of the acid producing fermenting pot is below 4, raising the pH value to 5.5, and stopping supplementing the waste fermenting liquid of methane phase.