ZnO film is attracting more attention because of its ultraviolet emission at room temperature and its potential applications in ultraviolet photoelectron devices in recent years.For the applications preparation of good-quality ZnO films and strong ultraviolet emission in films are requested.Annealing in different ambiences is a good method to improve the quality and to change the stoichiometrical composition.ZnO films were prepared by direct current reaction sputtering and annealed in different oxygen partial pressures(

P

O

2

).The laser lasing on the films was observed from the time resolution spectrum.X-ray diffraction analysis shows that the crystal constants decrease and the gain sizes of films increase with

P

O

2

these analysis and images of films by atom force microscopy show that the qualities of ZnO films were improved by annealing in oxygen ambiences.The influences of annealing

P

O

2

on photoluminescence(PL)and its relation to native defects were investigated also.We found that the intensities of ultraviolet photoluminescence were increased with oxygen partial pressures in certain range of

P

O

2

due to the improvement of the structure of films.But in higher

P

O

2

ultraviolet intensities decreased and green intensities increased instead.We suggest that more excitation energy was transferred to green center because of the generation of more acceptors in higher

P

O

2

that these acceptors act as green emission center in the films

the refore UV was decreased

green was increased.The compositions analyses in depth of samples A and E by Auger electron spectra show that A film(annealed in pure N

2

ambience)has stoichiometry of [Zn]/[O]

>

1 and Samples E(in pure O

2

)has that of [Zn]/[O]

<

1

it indicates there are more donor defects in Sample A and more acceptors in Sample E.The I-V curves of the junctions Sample E indicates the more acceptors generated in the ZnO film and may inversed to p-type semiconductor due to annealing in higher

P

O

2

.