Abstract: Calcium nitrate crystal can be obtained by freezing crystallization method from acid solution acquired from nitric acid extracting phosphate rock. After that，light calcium carbonate was prepared by carbonization reaction between ammonium hydrogen carbonate and calcium nitrate crystal.Results show that，the initial carbonization reaction temperature was the normal temperature，mass fraction of calcium nitrate solution was about 23%，ammonium hydrogen carbonate and ammonia dosages were both 110% of theoretical addition amounts，and products were washed by four times of product weight washing water.All quality indexes of the product can meet the standard of Industrial Precipitated Calcium Carbonate，HG/T 2226—2000.

Key words: calcium nitrate, ammonium hydrogen carbonate, carbonization, light calcium carbonate