NOVELTY - Landfill leachate is rested and deposited in an expanding granule sludge bed (EGSB) anaerobic reactor, and granular impurities are removed. The leachate has chemical oxygen demand of 10000-100000 mg/L. The leachate is supplied to bottom of reactor, and flows upwards through reaction region. The granule sludge in reaction region contains acid-forming bacteria and methanogen. Anaerobic fermenting reaction is carried out to produce marsh gas methane. The chemical oxygen demand of processed liquid is reduced to 200-5000 mg/L. Thus, methane is produced using leachate.    USE - Resource preparation of marsh gas using landfill leachate.    ADVANTAGE - The landfill leachate is effectively utilized, and methane gas is produced at high yield.    DETAILED DESCRIPTION - Landfill leachate is rested and deposited in an expanding granule sludge bed (EGSB) anaerobic reactor, and granular impurities are removed. The leachate has chemical oxygen demand of 10000-100000 mg/L. The leachate is supplied to bottom of the anaerobic reactor, and flows upwards through a reaction region of main portion of the device. The granule sludge in the reaction region contains acid-forming bacteria and methanogen. The granule sludge produces anaerobic fermenting reaction to produce marsh gas methane. The marsh gas methane is passed through a three-phase separator at top of the reactor and flows out from a gas outlet. The marsh gas product is collected. The reaction temperature is 10-40 degrees C. An insulating water bath jacket is provided outside the reactor. The pH of the leachate is controlled to 7-8, and adjusted by alkali liquor such as sodium carbonate. The load of the reactor is 10-70 kgCOD/m3.d. The flowing speed of the liquid in upward direction is 1-6 m/hour. The staying time of water power is 2-70 hours. The inlet chemical oxygen demand concentration of leachate is 10000-100000 mg/L. 80% of organic substance contained in leachate is transformed into methane. The chemical oxygen demand of processed liquid is reduced to 200-5000 mg/L. The gas production rate of methane is 5-25 L/L.d. Methane (5-25 l) is produced by the reactor per day.