Mn-doped ZnO nanocrystal was prepared on Si substrates by cathodic electrodeposition. X-ray diffraction (XRD) study suggested Mn ions substituted Zn position in ZnO crystal. Field-emission scanning electron microscopy (SEM) images showed the morphology of ZnO nanocrystal was column-like. In photoluminescence spectrum, the visible emission band was broadened because of the doping effect. The fitted result of the temperature-dependent PL spectra in the range from 122.8K to 302.2K showed that Mn dopant could result in the decrease of the exciton binding energy.