FLT3, a transmembrane molecule, was found on hematopoietic stem/progenitor cells and leukemia cells and determined to be a promising target in leukemia diagnosis and therapy. In this study a functional anti-human FLT3, monoclonal antibody (MAb) 10G6, was obtained and the specificity of this MAb was verified by flow cytometry. This MAb effectively recognized the FLT3 molecule expressed on a series of malignant cell lines. Furthermore, we demonstrated that MAb 10G6 inhibited the proliferation and migration ability and induced the apoptosis of SHI-1 cells that derived from a human monocytic leukemia. This functional anti-human FLT3 MAb provides a valuable tool for further study targeting the FLT3 on leukemia cells.