The growth kinetics of calcite crystals are studied in a batch-fluidized-bed crystallizer, which is maintained at a constant pH. The growth experiments are conducted in the metastable region explored as part of this research. The crystal growth rates are evaluated from the consumption rates of calcium ions, using the cured natural calcite or silica sand as seeding materials. Several operation variables are investigated, including supersaturation, pH, ionic strength, superficial velocity and particle size and type of seen. The significant factors that affect the crystal growth rate are identified. Then the crystal growth data of constant pH and ionic strength are analyzed by the two-step growth model. The mass-transfer coefficients are obtained and compared at various crystal sizes and superficial velocities. Finally, a growth-rate equation of calcite crystal, which is based on the two-step growth model, is proposed for design purposes.