Abstract: Sample of food with high calcium content was digested with HNO3 in a porcelain crucible by heating at low temperature, and evaporated to near dryness. The residue was taken up with HNO3 (1+99), and made up to 25 mL. Calcium in the sample solution was then determined by GF-AAS with Mg(NO3)2 added as matrix modifier. Temperatures of 750 ℃ and 1 100 ℃ were chosen for ashing and atomization respectively in the operation of graphite furnace. Linearity range of calcium was kept in the range within 5 μg·L-1 with detection limit (3s/k) of the method 3.3 μg·kg-1. The proposed method was applied to the analysis of samples of calcium supplementary food, and values of recovery obtained by standard addition method were in the range of 90.0%-103.3%. Values of RSD′s (n=7) found were ranged from 2% to 3%.