NOVELTY - Domestic sewage treatment system comprises black water gathering system, anaerobic acidification reaction tank, anaerobic gasification reaction tank and aerobic contact oxidation pond, where the black water gathering system is connected with the bottom of the anaerobic acidification reaction tank though black water inlet, and the outlet of the anaerobic acidification reaction tank is connected with the inlet of the anaerobic gasification reaction tank. The outlet of the anaerobic gasification reaction tank is connected with inlet of the aerobic contact oxidation pond.    USE - The domestic sewage treatment system is useful for residential community (claimed).    ADVANTAGE - The system is simple, has good sewage treating effect, and low project cost, and occupies small space.    DETAILED DESCRIPTION - Domestic sewage treatment system comprises black water gathering system, anaerobic acidification reaction tank, anaerobic gasification reaction tank and aerobic contact oxidation pond, where the black water gathering system is connected with the bottom of the anaerobic acidification reaction tank though black water inlet, and the outlet of the anaerobic acidification reaction tank is connected with the inlet of the anaerobic gasification reaction tank. The outlet of the anaerobic gasification reaction tank is connected with inlet of the aerobic contact oxidation pond, and the inlet of the aerobic contact oxidation pond is connected with brown water gathering system. The outlet of the aerobic contact oxidation pond is connected with aerobic sieve tower, and the inlet of the aerobic sieve tower is installed to grey water gathering system. The top of anaerobic acidification reaction tank and anaerobic gasification reaction tank is connected with biogas gathering tank which is connected with gas-fired boiler that supplying heat to the anaerobic gasification reaction tank. The gas-fired boiler is connected with inside of the anaerobic gasification reaction tank though pipe, and the inlet of the anaerobic gasification reaction tank is connected with alkali liquor addition system through pipe. An INDEPENDENT CLAIM is also included for treating domestic sewage using the system, comprising: (a) separately gathering black water, brown water and grey water in different gathering system; (b) letting black water into anaerobic acidification reaction tank and treating, separating sludge and sewage though the one-three phase separator, obtaining organic acid and little gas; (c) controlling the temperature of the anaerobic gasification and online temperature measuring device to monitor the temperature in the anaerobic acidification reaction tank, controlling the temperature of the gas-fired boiler for regulating gas quantity through regulator control system, maintaining water temperature in the anaerobic gasification reaction tank at 35-38 degrees C, controlling the pH value in the anaerobic gasification reaction tank, letting acidized water in anaerobic gasification reaction tank, adding alkali liquor in the tank, regulating the pH value in the anaerobic gasification reaction tank to 6.8-7.2 through the alkali liquor addition system and the acid-base online measuring device, and treating it with organic acid to obtain methane gas; (d) gathering the gas from step (b) and step (c) in biogas gathering tank as fuel gas; (e) mixing brown water of brown water gathering system and the sewage after anaerobic treatment in aerobic contact oxidation pond and proceeding aeration treatment, where the aeration rate of the aeration regulator control system is required to maintain dissolved oxygen in water to not greater than 2 mg/l; (f) mixing grey water of grey water gathering system and the sewage after aerobic treatment and passing into aerobic sieve tower, filtering and obtaining clear water; (g) pumping clear water after filtering from the sump tank into clean water basin through water pump, and connecting the outlet of the clean water basin to recycle water bolt to spare; and (h) discharging redundant sludge into anaerobic acidification reaction tank, anaerobic gasification reaction tank and aerobic contact oxidation pond though sludge discharge pipe, refluxing part of sludge of aerobic contact oxidation pond in anaerobic acidification reaction tank through the sludge return pipe.