ZnO and Al-doped ZnO thin films were prepared by sol-gel dip-coating method and electrical and optical properties of films were investigated. Using the zinc acetate dihydrate and acetylaceton(AcAc) as a chelating agent stable ZnO sol was synthesized with HCl catalyst. Adding aluminium chloride to the ZnO sol Al-doped ZnO sol could be also synthesized. As Al contents increase the crystallinity of ZnO thin film was retarded by increased compressive stress in the film resulted from the difference of ionic radius between Zn2+ and Al3+ The thickness of ZnO and Al-doped ZnO thin film was in the range of 2100~2350$AA$. The resistivity of ZnO thin films was measured by Van der Pauw method. ZnO and Al-doped ZnO thin films with annealing temperature and Al content had the resistivity of 0.78~1.65$Omega$cm and ZnO and Al-doped ZnO thin film post-annealed at 40$0^{circ}C$ in vacuum(5$ imes$10-5 torr) showed the resistivity of 2.28$ imes$10-2$Omega$cm. And the trans-mittance of ZnO and Al-doped ZnO thin film is in the range of 91-97% in visible range.