Abstract: MgCO₃·3H₂O precursor was firstly prepared by precipitation crystallization reaction with MgSO₄ as raw material and with（NH₄）₂CO₃ as precipitator.MgO whisker was then prepared by appropriate filtering,drying，and calcining processes. Influences of reaction temperature,amount-of-substance ratio of reactants,titration rate of（NH₄）₂CO₃，and initial  concentration of MgSO₄ on the crystal growth and morphology of precursor were investigated.Precursor and final crystals were characterized by XRD and SEM.Results showed that the reaction temperature,amount-of-substance ratio,titration rate and initial  concentration of MgSO₄ all had significant effect on the crystal growth,morphology，and particle size.Process conditions were also optimized by experiments.It was supposed that the production and growth mechanism of whisker was liquid-liquid-solid （L-L-S） mechanism,which was based on screw-dislocation growth.

Key words: basic magnesium carbonate, MgSO₄, MgO