A method for determining the content of calcium element in an ore is provided. It includes: decomposing the ore with hydrochloric acid and nitric acid under heating condition, adding perchloric acid, cooling, adding a small amount of water and boiling the solution to dissolve the salts, then cooling, diluting to the constant volume, filtering into a dry beaker with dry filter-paper, masking interfering ions with triethanolamine, adjusting the pH value of the solution with KOH, using calcein-thymolphthalein as indicator, and determinating the content of calcium with EDTA titrimetry.