The photoluminescence spectrum of ZnO film with high crystal quality has been measured. The peak of near-ultraviolet emission located at 389 nm has been observed. For the ZnO film treated by ultrasonic, not only the ultraviolet peak of ZnO, but also the strong green peak at 508 nm have been observed. It is also found that the intensity of the green peak (508 nm) is stronger than that of the ultraviolet peak. The ultraviolet peak also appears to have red-shift. The intensity of the green peak (508 nm) increases sharply with further heating. The crystal quality of ZnO films is changed by the ultrasonic treatment and oxygen vacancies are produced. The lattice vibration of film is aggravated in the treatment process. When the lattice vibration arrives at certain degree, the lattice oxygen leaves the lattice site to form oxygen vacancy, and the green peak (about 510 nm) is attributed to oxygen vacancies in the crystal. The density of oxygen vacancies depends on the ZnO film temperature. The higher the film temperaure, the greater the density of oxygen vacancy and the stronger the intensity of the green peak.