This study was aimed to investigate the reversal effect of tyrosine kinase inhibitors (TKI) Imatinib and Nilotinib on multidrug-resistant cell line K562/A02. The expression levels of mdr-1 mRNA and bcr-abl mRNA were assayed by RT-PCR. The protein levels of P-glycoprotein (P-gp) and P210 were detected by Western blot. The daunorubicin (DNR) accumulation in K562/A02 cells were analyzed by flow cytometry (FCM). The results showed that the 0.0625 micromol/L Imatinib or 5 nmol/L Nilotinib alone had no cytotoxic effect on the inhibition of K562/A02 cells. When K562/A02 cells were treated with Imatinib or Nilotinib alone for 48 hours, the expressions of mdr-1 mRNA, der/abl mRNA, P-gp and P210 protein were all down-regulated, furthermore the effect of Nilotinib was stronger than that of Imatinib. The detection of fluorescence intensity revealed that the DNR concentration in K562/A02 cells treated with Imatinib or Nilotinib alone for 48 hours were 7.85% and 12.02% of K562 cells respectively. It is concluded that the tyrosine kinase inhibitors show great effect reversing drug resistance of cells, moreover, the effect of Nilotinib is stronger than that of Imatinib.