Abstract: To enhance the sulfate reduction efficiency, the effects of temperature, influent pH, HRT, ρ(COD)/ ρ(S $\begin{array}{c}{O}_4^{2-}\end{array}$ ) and reflux ratio on the sulfate reduction were discussed by using small space anaerobic moving bed biofilm reactor. Then the reducing S $\begin{array}{c}{O}_4^{2-}\end{array}$ efficiency and stable operation were also studied under high load conditions. Results indicate that the optimal conditions for reactor operation is at temperature 35℃, influent pH=7.0, ρ(COD)/ ρ(S $\begin{array}{c}{O}_4^{2-}\end{array}$ )= 2.5, HRT=8h and reflux ratio=4∶1. When the sulfate reduction rate remains in the range of 78.77%-88.89% and sulfate concentrations ranges from 1500 to 2500mg/L; sulfate removal rate is up to 5.90kg/m ³·d and there is a high S $\begin{array}{c}{O}_4^{2-}\end{array}$ reduction capacity in reactor. When the condition of the influentsulfate concentrations is 2250mg/L and continuous reactor operation for 20d, the sulfate removal efficiency reaches more than 87.13% and the reactor keeps stable operation.