The invention provides a sewage treatment system, which comprises a sewage filtering device, a sewage precipitation and concentration device, a marsh gas generating device, a combustion engine electric generating set and a sludge drying device, wherein high-temperature smoke gas generated after the electric generation of the combustion engine electric generating set is respectively conveyed to theprecipitation and concentration device, the sludge drying and the marsh gas generating device. The sewage treatment system provided by the invention can realize solid liquid separation and secondaryutilization; the burden on the biological digestion function of natural environment is reduced as much as possible; the self-sufficiency of the self-consumption energy source of a sewage treatment plant is realized; the sewage treatment cost is reduced to the minimum. The sewage treatment system provided by the invention has the advantages that the process facilities can be simplified; meanwhile,the goals of reducing the cost, increasing the yield, realizing the near zero emission and the like are achieved; great economic values are realized; the sewage treatment system is suitable for beingpopularized and used.