NOVELTY - A sludge treatment system comprises former processing unit, hydrothermal unit, cooling and dewatering unit, water treatment unit, vapor generating unit and methane purifying unit. The former processing unit comprises raw material storage bin for temporarily storage sludge and deodorization unit for whole unit system deodorization. The hydrothermal unit is composed of homogeneity jar, slurrying reactor, thermal reactor and flashing evaporation reactor, where the raw material storage is connecting with homogeneity jar. The cooling and dewatering unit is composed of cooler and filter press.    USE - For producing compressed natural gas (CNG) (claimed); and for municipal sludge treatment.    ADVANTAGE - The sludge treatment system provides good processing effect and volume reduction effect; provides high accuracy of pigment application; and greatly improves urban ecological environment and city commercial appearance.    DETAILED DESCRIPTION - A sludge treatment system comprises former processing unit, hydrothermal unit, cooling and dewatering unit, water treatment unit, vapor generating unit and methane purifying unit. The former processing unit comprises a raw material storage bin used for temporarily storage sludge and a deodorization unit for whole unit system deodorization. The hydrothermal unit is composed of the homogeneity jar, slurrying reactor, thermal reactor and flashing evaporation reactor, where the raw material storage is connecting with the homogeneity jar. The cooling and dewatering unit is composed of cooler and filter press. The flashing evaporation reactor is connecting with the feeding end of the cooler. The dehydrated filtrate of the filter press leads to the sewage treatment factory after passing through the medium temperature anaerobic reactor of the water treatment unit. The dehydrated mud cake of the filter press leads to the fuel feeding inlet of the vapor generating unit, where the vapor generating from the vapor generating unit supplies the thermal reactor and flashing evaporation reactor, and the methane discharging end of the medium temperature anaerobic reactor leads to the methane purifying unit to prepare and obtain compressed natural gas (CNG).    DESCRIPTION OF DRAWING(S) - The figure shows diagram of a sludge treatment system structure.