The surface functionalized non-biotoxicity detonation nanodiamond (DND) has been proposed to combine with all trans retinoic acid (ATRA) for enhancing the efficacy of ATRA drug on the typical target cancer cell of HL-60 of acute promyelocytic leukemia (APL). Treated by the DND–ATRA complex, the inhibition and apoptosis rates of HL-60 cells are significantly increased higher than that treated by sole ATRA. A large amount of ATRA can be absorbed on the surface-functionalized DNDs, and release in the cancer cells with a high local concentration. The drug delivery of DND might present an important way for improving the pharmacodynamics of ATAR for the treatment of leukemia cell.