The effect of Mg(2+)on the crystallization of precipitated calcium carbonate (PCC) via a bubbling carbonation method and the mechanism of eliminating its influence by glucose were investigated. The polymorph and morphology of crystals were characterized by field emission-scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. These results demonstrated that Mg(2+)and Mg/Ca molar ratio played significant roles on the morphology of PCC. When the Mg/Ca molar ratio was below 0.5, only spindle-like calcite formed. The rod-like aragonite started to form when the ratio was 0.6. As the ratio increased, the amount of aragonite increased and the length of rod-like aragonite became longer. Notably, the effect of Mg(2+)could be eliminated efficiently when the 1.5 wt% glucose was added into the carbonation system, in which system, the PCC crystals were all spindle-like calcite. Furthermore, the mechanism of the glucose to eliminate the influence of Mg(2+)on PCC crystallization was proposed.