Abstract: The sugar industry is acknowledged crucial importance to the national economy and people′s livelihood.Emis- sions and wastes are becoming the bottleneck problems to the Chinese sugar industry′s survival and sustainable development. The effect of molecular weights of dextran on the calcium carbonate obtained by simulated flue gas carbonation in the calcium saccharate solution was investigated by focused beam reflectance measurement（FBRM），scanning electron microscope（SEM）， infrared radiation（IR）， and X-ray diffraction（XRD）.The morphology of the calcite was changed from bifurcation stalactite into irregular shape with the increasing of dextran molecular weight. In addition，both of chord length range and unweighted median chord length of the calcite decreased with the increase of the dextran molecular weight.The dextran in the calcium saccharate solution could not cause lattice distortion in the calcium carbonate.The research results make a theoretical and technical foundation for the green processing and energy savings of sugar industry in the future.

Key words: flue gas, dextran, calcium carbonate, calcium saccharate solution