Objective To study the effect of tetrandrine on K 562 cells and its possible mechanism. Methods Light microscope,electron microscope and immuno fluorescence staining were used to detect the morphological changes of K 562 cells,to analyse the cell cycle of K 562 cells FCM was performed,to detect the expression of Bcl 2 gene and wild type p53 gene in K 562 cells ABC method was carried out,and to detect in cell death TUNEL method was applied. Results K 562 cells treated with tetrandrine for 48?h showed early changes of apoptosis.DNA synthesis was reduced.Bcl 2 expression was decreased while wild type p53 gene expression was increased.TUNEL showed DNA breakage.Conclusion\ Tetrandrine inhibits the growth of K 562 cells.The effect is related with the concentration used.Tetrandrine can induce apoptosis of the cell.