Abstract: The influence of magnesium and citrate ion on the growth of calcium carbonate crystals under the control of soluble chitosan was investigated by means of X-ray diffraction,scanning electron microscope and thermal analysis.Under the control of soluble chitosan,the growth of vateriate was promoted.With the increase of soluble chitosan,the content of vateriate cryastal was increased.However,in the presence of the Mg²⁺,the formation of calcite crystal was encouraged.In addition,the influence of single citrate ion on the growth of calcium carbonate was not obvious,yet under the control of Cit^3- and soluble chitosan,the growth of vateriate was promoted significantly which was higher than the only soluble chitosan.