Abstract: According to the simplified flowpattern of an up-flowanaerobic sludge blanket (UASB) reactor, a structural optimization model is constructed. Through solving the optimization model and analyzing the correspondingresults, it can be concluded that (1) the structure design of the UASB reactor must be focused on the technical development in both the water distribution system and the three-phase separator to increase volumetric efficiency; and that (2) the combination forms oftheUASB reactorwithother processing structures should be developed due to the difficulty of increasing the hydraulic load in a common UASB reactor.