To study the crystalline structure, surface morphology and optical property changes of AZO thin films prepared under various O2 partial pressures, pulsed-laser deposition ( PLD) was used to deposit AZO thin films on glass substrates.The results showed that AZO thin films grew along with preferential orientation (002) and had optimal crystalline quality when oxygen partial pressure kept at 0.8 Pa.In addition, the films had smooth surface and compacted structure and nanocrystalline grains disposed evenly on the surface of films.It also can be found that the ultraviolet absorption edge moved to the longer wavelength with the increase of oxygen partial pressure from 0.2 Pa to 8.0 Pa. Oxygen partial pressure had little influence on the transmittance of AZO thin films in visible light re-gion and the transmittance of all the AZO thin films is above 80%.