Abstract: Molasses alcohol wastewater normarlly contains high quantity of SO42- which can restrain the production of the biogas. In this paper, we used the activated carbon, BaCl2?2H2O, Ca(OH)2 and iron carbon micro cell to pretreat the molasses alcohol wastewater. Results showed that addition of 8.0 g activated carbon in 500.0 g molasses alcohol wastewater, the sulfate removal rate reached 80% and the gas production was the best which reached 437.3 mL/g. Activated carbon adsorption of sulfate can reach more than 80%, with a small amount of adsorption COD (<12%). Based on the content of S element and BaSO4 molecules, in the 500 g molasses alcohol wastewater, addition of 70% of BaCl2?2H2O removed all sulfuric acid. The cumulative gas production rate reached 483.2 mL/g. In the same way, addition of 70% of Ca(OH)2 removed all the sulfuric acid, the cumulative gas production rate reached 436.6 mL/g, which is the relatively best. The removal rate of chemical reagents sulfate can reach 100%, and there was no effect on the COD. But the introduction of new ion could have a potential impact on the anaerobic fermentation. Calcium sulfate is slightly soluble in water, so the removal effects of sulfate is not better than that with BaCl2?2H2O pretreatment, though low Ca2+ concentrations can accelerate the formation of biofilm. Using the Iron carbon micro cell method to handle the molasses alcohol wastewater can effectively suppress the influence of sulfate and improve the wastewater treatment. For daily gas production rate, gas production cycle was shorter in the experimental group than the control group for 2 to 3 d. The first small peak gas production of molasses alcohol wastewater treated with iron-carbon micro-battery appeared in the first 12 d. The cumulative gas production rate with iron carbon micro cell addition can reach 451.0 mL/g which was 1.5 times of the control group. Iron-carbon micro-cell affected sulfate removal by producing iron sulfide and sulfate-reducing product FeS which precipitated in the wastewater. As such, the addition can improve the wastewater treatment. Although BaCl2?2H2O could improve sulfur removal and increase gas production in treating molasses alcohol wastewater, its high cost limited its application. The iron-carbon micro battery in the gas production, although slightly lower than BaCl2?2H2O had a low cost. The treatment effect of gas production performance was: 70% BaCl2?2H2O> iron carbon micro cell > 8.0 g activated carbon adsorption > 70% Ca (OH)2 > the control group.