In order to observe the effect of inhibitors for demethylation and histone deacetylase on the growth of leukemia cell line K562 and the expressin of tumor related genes, the K562 cells were treated with 5-aza-2' deoxycytidine (DAC) and trichostatin A (TSA) in co-culture; the growth curves were observed; the cell cycle was detected by flow cytometry (FCM); the gene expression pattern before and after drug treatment was measured with Atlas7742-1 microarray. The results showed that the combination treatment of DAC and TSA inhibited the proliferation of K562 cells, the growth of most cells were stopped in G(1)/S phases after drug treatment, the gene expression after treatment was more than before, and a few gene expression were down-regulated. In conclusion, combination treatment of DAC and TSA had an inhibitive effect on the leukemia cell line K562, combination of DAC and TSA with microarray could be used for screening candidate genes inhibiting leukemia cells.