Objective To study the role of transcription factor c-Myb in the pathogenesis of acute promyelocytic leukemia (APL). Methods Through analyzing microarray data of acute myeloid leukemia (AML) patients, we compared the levels of c-Myb expressions in APL cells and normal promyelocytic cells. Through inducing the differentiation of NB4 with ATRA and the expression of PML-RARα in PR9 cells with ZnSO4, we investigated whether c-Myb was involved in the pathogenesis of APL. Using RNAi, we researched whether knocking down c-Myb could rescue APL. Results The levels of c-Myb expression in APL cells were higher than those in normal promyelocytic cells. The expression of c-Myb gradually declined along with the differentiation of NB4, and gradually rose along with the expression of PML-RARα in PR9. The knockdown of c-Myb could rescue the blocked differentiation of NB4, which increased the positive rate of CD11b of NB4 cells to about 20%. Conclusion The level of c-Myb expression in APL is higher than that in normal promyelocytic cells, which indicates that c-Myb has an important role in the pathogenesis of APL. The knockdown of c-Myb can partly reverse APL.