Abstract: Jet-loop anaerobic fluidized bed (JLAFB) was designed as a new anaerobic reactor.Two-phase anaerobic digestion process with JLAFB and AGSFB (anaerobic granular sludge fluidized bed) as acidogenic phase (or sulfate-reducing phase) and methane-producing phase, respectively, was used to treat high concentration sulfate-organic wastewater.With the successful culture of acid-tolerant sulfate reducing anaerobic granular sludge, the process successfully separated sulfate reducing bacteria (SRB) and methane producing bacteria (MPB) in different phases, and avoided substrate competition inhibition on MPB by SRB.When influent SO2-4 loading rate was up to 12.0 kg SO2-4·m-3·d-1, the sulfide concentrations of JLAFB and AGSFB reactors were 78.3 mg·L-1 and 92.4 mg·L-1, respectively, that were far less than 200 mg·L-1 of inhibition value, which avoided the accumulation of sulfide and toxicity inhibition on microorganisms in reactors.When the influent COD and SO2-4 loading rates during smooth operation were 26.0 and 8.5 kg SO2-4·m-3·d-1 respectively, the total removal efficiency values of COD and SO2-4 were 86.9% and 97.6% respectively.The optimal process conditions of the treating system were:influent COD/SO2-4 ratio＞3.0，influent alkalinity was 400—500 mg·L-1,aeration gas flow rate and hydraulic recycle ratio of JLAFB were 0.04 L·min-1and 5∶1 respectively.