Near cube form calcite was prepared with light calcined dolomite powder, ammonium chloride and carbon dioxide as raw materials by ammonia-precipitation process without using crystal controlling agent. The effects of reaction temperature, calcium ion concentration in solution, aeration rate, agitation rate and aging time on the content of calcium carbonate and morphology of calcite phase in calcium carbonate were investigated, and the crystal type control mechanism of calcium precipitation reaction was studied. The results show that under the conditions of reaction temperature of 40 ℃, calcium concentration of 0.05 mol/L, carbon dioxide passing rate of 100 mL/min, stirring speed of 400 r/min and aging time of 2 h, near cube form calcium carbonate with regular morphology and uniform particle size distribution is prepared, with an average particle size from 5 μm to 10 μm. This study provides a theoretical basis for improving the use value of dolomite, producing calcium carbonate products with high added value and improving the utilization rate of dolomite resources.