Acute myeloid leukemia (AML) is the most common acute leukemia in adults. Despite improved remission rates, current treatment regimens for AML are often associated with a very poor prognosis and adverse effects, necessitating more effective and safer agents. B-cell leukemia/lymphoma 2 (Bcl-2) family proteins regulate apoptotic pathway that can be targeted with small molecule inhibitors. APG-1252-12A is a Bcl-2 homology (BH)-3 mimetic that specifically binds to Bcl-2 and Bcl-xl, which has shown efficacy in some Bcl-2 dependent hematological cancers. In this study, we investigated whether APG-1252-12A inhibits the growth of five leukemia cell lines in a concentration- or time-dependent manner by MTS assay. Following treatment of AML cell line HL-60 with this compound, cell apoptosis was detected using flow cytometry and nuclear condensation was observed after Hoechst 33258 dye. Immunoblotting for cytochrome c, cleaved caspase-3 and PARP-1 cleavage was used to demonstrate the mechanism of inducing mitochondria-dependent apoptosis by APG-1252-12A. Our findings showed that this new compound inhibited cell proliferation in five leukemia cell lines and induced apoptotic death. There was a link between the level of Bcl-2 protein and IC50. APG-1252-12A targeted mitochondria and induced caspase-dependent apoptosis by inducing the HL-60 cell cytochrome c released, PARP cleavage and caspase activation. These data suggested that APG-1252-12A is a candidate drug for the in vivo analysis and clinical evaluation in AML.