Reducing titanium dioxide gypsum of by-product of titanium dioxide production by sulfuric acid method with sulfur and carbon is one of the methods to deal with the stacking problem of titanium dioxide gypsum.Aiming at the problems of long time,large amount of sulfur and low output of calcium sulfide in the process of decomposing titanium dioxide gypsum to sulfuric acid and calcium oxide in rotary kiln.It was pointed out that using titanium dioxide gypsum as raw material,after removing iron impurities by acid leaching,gypsum was calcined in gas-solid vertical reactor with sulfur as reducing agent to produce calcium sulfide and sulfur dioxide.The former was calcined with calcium sulfate to obtain calcium oxide and sulfur dioxide.The obtained calcium oxide could neutralize waste acid and wastewater,and the generated sulfur dioxide was used to prepare sulfuric acid.The experimental scheme was determined by reaction thermodynamics analysis by HSC software.After fluidization experiment（800 ℃,40 min for heat preservation） and calcination experiment（1 100 ℃,1.5 h for heat preservation）,the conversion rate of calcium sulfide and purity of calcium oxide were both about 90%.Then the process flow was simulated by using Aspen software,the volume fraction of SO₂ could reach 12.09%,which could meet the requirement of sulfuric acid production.The production cost of sulfuric acid was estimated to be 263.9 CNY/t,which had a great market prospect.