Abstract: Low cost technology of calcium remove was explored.The low calcium lanthanum oxide preparation technology use high calcium lanthanum chloride (LaCl<SUB>3</SUB>) solution as raw material,and ammonium bicarbonate solution as precipitating agent.By studying the influences of adding way of ammonium bicarbonate solution,effective factors such as adding amount of seed crystal and aging time&nbsp; on calcium content of lanthanum oxide,optimum technological conditions were obtained.Reproducibility test was also carried out and lanthanum oxide sample with mass fraction of CaO less than 5×10<SUP>-4</SUP>was prepared. 