Abstract: In order to explore the origin of room-temperature magnetic properties in ZnO diluted magnetic semiconductor materials, ZnO powders with Mn content of 0, 1%, 2% and 3% were prepared by sol-gel method respectively. The morphology, phase, electronic structure, and magnetic properties of samples were studied by using X-ray diffractometer (XRD), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and vibrating sample magnetometer (VSM). The results show that the particle sizes are decreased through doping Mn into ZnO. Mn replaces Zn in the form of ion, and its phase structure keeps the hexagonal wurtzite of ZnO. There are no secondary phases in doping samples. The Zn-Mn bond and Mn-O-Mn bond are formed in Mn-doped ZnO, and they change the defect structure of intrinsic ZnO, so magnetic properties of samples are changed. The room-temperature magnetic property of ZnO is determined by the concentration of oxygen vacancy. The optimum content of Mn is 1%, and its maximum saturation magnetic moment is 22.599×10⁻² emu/g.