Aragonite calcium carbonate whisker was prepared by thermal decomposition of Ca（HCO3）2 in aqueous solution in the presence of chloride salts. The influences of reaction temperature, time and concentrations of CaCl2, MgCl2 and KCl on the morphology of CaCO3 whiskers were studied. The structure characteristics of CaCO3 whiskers were analyzed by XRD and SEM. The results indicate that the optimum conditions are 80～100 ℃, 50～60 min and the suitable concentrations of Ca（HCO3）2, KCl, MgCl2, CaCl2 are 6.0 mmol/L, 14.0 mmol/L, 1.0 mmol/L, 1.5 mmol/L respectively. The purity of the whiskers is 99.53% and the average aspect ratio is 24.1.
