Ultra-fine cenospheres modified with CaCO3 were synthesized by surface liquid deposition method.Both the original and modified cenospheres were characterized by SEM,EDX,XRD,and colorimetric tube techniques.The results show the modified cenospheres'color is changed from gray black to light gray,and the mean size of modified cenospheres is 1.94μm which is grown by 7.8% than original cenosphere.The modified ecosphere's area is 2.4m2/g,which is larger about 26.3% than that of original cenosphere.The density of modified cenosphere is in-creased and according to the formula,it could be calculated that the thickness of cenosphere is grown by 30%.The original and modified cenosphere is dispersed by dispersant,and testing indicates that the dispersion stability properties of modified cenosphere are far more improved.