Abstract: Because of the chemical and biological reactions in an up-flowanaerobic sludge blanket (USRB) reactor, the inner surfaces of the UASB reactor are easy to corrode, so that the reaction efficiency and the service life of the reactor are decreased and the maintenance cost is increased. In this paper, based on the analysisof the effects of the structure of UASB reactors and the processes of reactions on corrosion, the corrosion mechanism is discussed, and three measures to prevent the corrosion of the UASB reactor are presented,i.e., improvement of the anticorrosion design, application of anticorrosion materials and preservative treatment of the equipment.