NOVELTY - Utilizing biogas generated in pig farming involves: construction of marsh gas tank; directly using biogas for producing hot water; cooking fuel; heat preserving; generating marsh gas; using biogas residue as organic fertilizer; recharging the farm biogas liquid; and using the biogas residue and spraying it on the leaf surface.    USE - For utilizing biogas generated in pig farming (claimed).    ADVANTAGE - The present method meets environmental requirements; greatly improves the effective recycling and comprehensive utilization of resources; and provides good economic, environmental and social benefits.    DETAILED DESCRIPTION - Utilizing biogas generated in pig farming involves:    (A) construction of biogas pool by selecting direction of the water outlet of biogas tank, based on the number of pigs, and daily gas consumption, determining the rate of gas per cubic meter of volume of 0.15 m3 biogas circulation, determining volume of farm size and size of the digester biogas and testing the water and pressure to ensure a good seal;    (B) circulating hot water through the installation of thermal insulation of pipes; adding distilled water; igniting directly to heated floor insulation; and cooking the fuel;    (C) generating marsh gas after desulfurization, separating steam water, mixing with air, through the turbine pressurizing device into the engine combustion chamber, through electronic control technology, using of closed-loop automatic adjustment of combustion air-fuel mixture drives the engine set generation, heating circulating cooling water to 90 degrees C;    (D) replacing the biogas storage fresh indoor air, reducing the oxygen content, reducing fruit respiration rate, decreasing their metabolism, delaying ripening period, so as to achieve a more prolonged preservation and storage, where the chamber has gas permeable area of 10-15 m2, and volume of 25 m3;    (E) stacking biogas residue and water, where the moisture content is 60-70% to obtain fertilizer, where the fertilizer comprises urea, diammonium phosphate, potassium sulfate slag and biogas residue in mass ratio of 22-32:5-9:2-6:48-65 respectively; and    (F) using the biogas residue and spraying it on the leaf surface for 3-4 days.