Shellfish samples were prepared by microwave, and 27 microelements including Ca, Mg, K, Na, P, S, Zn, Mn, Fe, Cu, Cr, Co, Se, Sn, Ni, Al, Ti, V, Mo, Ba, Ge, Si, Cd, I, Pb, As and Hg were determined by ICP-AES. It was showed that ICP-AES had an obvious advantage in the determination of microelements, and shellfishes contained upwards of 20 kinds of microelements. Calcium in fresh water was higher than that in seawater, and As and Pb were the major pollutants.