This study was aimed to evaluate the effect of triptolide (TPL) on the reversal of multidrug resistance in K562/A02 cell line. The sensitivity of K562 and K562/A02 to adriamycin (ADM) and reversal of drug resistance were determined with MTT method. The concentration of intracellular ADM and P-glycoprotein expression were detected by flow cytometry. Luciferase reporter gene assay was used to detect the transcriptional activity of MDR1 promoter. The results showed that TPL significantly decreased the resistance degree of K562/A02 cells, inhibited P-glycoprotein expression (mean fluorescent intensity decreased from 123 ± 13 to 39 ± 13) and increased the intracellular concentration of ADM (mean fluorescent intensity increased from 18 ± 5 to 34 ± 6) in K562/A02 cells. Luciferase reporter gene assay demonstrated that TPL inhibited the transcriptional activity of MDR1 promoter by 75%. It is concluded that TPL may effectively reverse the multidrug resistance in K562/A02 cells via modulating P-glycoprotein expression and increasing intracellular ADM accumulation.