Abstract: TG-DSC-FTIR was used for on-line detection to study the gas release characteristics during the calcination of sulfur fixation agent for cement raw meal. The calcination process was simulated on a TG-DSC comprehensive thermal analyzer. The composition of gas products was identified by FTIR. It was found that in the calcination process of sulfur fixation agent for cement raw meal at 35-1 450 ℃, CO₂, H₂O and SO₂ gases were mainly released, and four reaction steps occurred in the whole calcination process. The first step is desorption of adsorbed water and gypsum dehydration (crystal water). The peak value of H₂O integral flow is 121.56, 154.72 ℃, and the total weight loss is 3.19%. The second step is the removal of crystal water from mineral phase, the weight loss is 0.29%, and the peak value of H₂O integral flow is 423.83 ℃. The third step is the decomposition of calcium carbonate, the weight loss is 24.40%, and the maximum value of integral flow of CO₂ gas is 818.87 ℃. At 819.54 ℃, the peak of H₂O integral flow appeared to be the minimum. The fourth step is the decomposition of calcium sulfate, and the total weight loss is 1.83%. The integral flow of SO₂ gas showed a maximum release at 1 415.69 ℃.