Needle-like nanometer calcium carbonate was prepared by intermittent carbonation method, and the mechanism of synthesis was discussed. The influences of the reaction conditions, such as reactants concentration, temperature, additives etc, were studied. The result showed that the additives and the time to add were the key factor of polymorph and the shapes of calcium carbonate particles in carbonate processing. Nanometer calcium carbonate powder which the average diameter was between 40 and 50nm and the aspe...