Abstract: In allusion to the identification of nutritional elements，such as Zn，Fe and Mg in the nano-sized medical oyster calcium carbonate，the flame atomic absorption spectrometry was adopted to determine their contents.The determination conditions were optimized and the linear range，detection limit，precision and recovery rate of the method were investigated as well.The linear equations are：Zn：Y=0.157 1 x+0.000 7；Fe：Y=0.048 9 x-0.000 1；and Mg：Y=0.456 1 x+0.000 5，respectively.The detection limits of the three elements are： ρ(Zn)=0.05 mg/L； ρ(Fe)=0.1 mg/L；and ρ(Mg)=0.01 mg/L.Recovery rates are：Zn，99.31%；Fe，98.13%；and Mg，99.89%.Results showed that the nano-sized medical oyster calcium carbonate is reach in Fe，Zn and Mg， which are good for human health.The flame atomic absorption spectrometry is simple，convenient，and of good repeatability and accuracy for the determination of nutritional elements.