Desulfurization is the prerequisite of high-sulfur bauxite comprehensive utilization. Researches of roasting characteristics of high-sulfur bauxite provide foundations for developing a new desulfurization technology. Coupling test of thermal analysis and Flourier transform infrared (FTIR) spectrum analysis was carried out for high-sulfur bauxite with sulfur content of 4.32% from Guizhou. The types, process and main characteristics of reaction occurring during oxidation roasting process of high-sulfur bauxite were comprehensively analyzed and studied by TG, DTG, DSC and FTIR coupling method, and the development of new desulfurization process with suspension state was discussed. A new approach for infrared spectroscopy analysiswas developed to separate the release features of various components from the infrared spectroscopy of gaseous product mixture, and it was used to separate the desulfurization process and dehydration process of high-sulfur bauxite. Results showed that: The main reactions of high-sulfur bauxite in the roasting process were dewatering of diaspora, oxidation desulfurization of pyrite and decomposition of calcite. The gaseous products of the reaction were H2O(g), SO2 and CO2. Dewatering of diaspora was a single step reaction, which appeared in the range of 380.0~580.0 ℃. The reaction of oxidation of pyrite is two step reaction, and which appeared in the range of 388.0~574.0 ℃. The decomposition temperature range of calcite was at 700.0 to 860.0 ℃. The quantity of desulfurization of high sulfur bauxite can directly compensate the endothermic quantity of the dehydration. The suitable operation temperature for suspension state desulfurization process was 580.0~650.0 ℃. The conclusions of this paper can serve as references developing a new suspension desulfurization technology for high-sulfur bauxite.