In this study, in order to determine the carbonation process relationship between cement hydrates and calcium carbonate polymorph, Raman spectroscopy was applied to measure the carbonation process of ordinary Portland cement and Alite cement paste at different relative humidity. As a result, carbonation of both cement paste was most progressed in the wet environment, while almost no carbonation progress in the dry and 60%RH condition. Calcite and vaterite were the main precipitates in the carbonation of ordinary Portland cement, while calcite was the main precipitate in the carbonation of Alite. The correlation coefficient between cement hydrates and calcium carbonate, and the carbonation rate of cement hydrates were obtained by Raman mapping data.