Abstract: The morphology and structure of sub micron spindle like calcium carbonate synthesized by gas liquid carbonization method were analyzed by TEM, XRD, etc. The effects of initial carbonation temperature and morphology control additive amount were studied. The results show that the sub micron CaCO3 with radial length of 200—600 nm and the ratio of radial length to axial length of 4 can be prepared at the initial temperature of 30—35 ℃ and with (NaPO3)6 mass fraction of 0.8%—1.2%. Furthermore, the main effect of crystallization controller (NaPO3)6 is to promote the nucleation rate and increase the steric hindrancefor Ca(OH)2 crystallization.