Abstract: OBJECTIVE To investigate the component elements in the water decoction of traditional Chinese mineral drugs Danfan, and the most important element associated with the inhibition rate of A549 cells in vitro. METHODS the total elements in the water decoction of traditional Chinese mineral drugs danfan were analyzed by ICP-MS. the inhibition ratio of different elements of water decoction of Danfan to the A549 cell were detected by MTT assay. Then the Grey relational grade between the inhibition ratio and elements was analyzed, and flow cytometry was used to verify the results that which element was promoting apoptosis of lung tumor cells. RESULTS The main elements of the water decoction of danfan were Cu, Zn, Fe, Cd, Mn, Al, Na, Ca and so on. The correlation coefficient between Cu and A549 cell inhibition rate was the largest. The flow cytometry research further validated that which elements promoting apoptosis of lung cancer cells. CONCLUSION The copper element in Danfan is an important element in the tumor cell apoptosis activity.