[en] Room-temperature ferromagnetism (RTFM) has been observed in RF magnetron sputtered ZnO films with O₂ as an auxiliary gas after annealing. The films exhibit hexagonal wurtzite structure and observable ferromagnetism. A maximum of saturation magnetization of 4.75 emu/cm³ is obtained. The zinc vacancies are believed as the RTFM origin, and oxygen vacancies are not an incentive of magnetization of the ZnO films. Theoretical study based on first principles calculation is performed for better understanding of the RTFM in substance. The intrinsic physical mechanism of regulating the ferromagnetic of the ZnO film is analyzed in detail.