In this study Al-doped ZnO (AZO) thin films have been fabricated on Eagle 2000 glass substrates at various substrate temperature ($100{sim}500^{circ}C$) and working pressure (10 ~ 40 mTorr) by RF magnetron sputtering in order to investigate the structural, electrical, and optical properties of the AZO thin films. The obtained films were polycrystalline with a hexagonal wurtzite structure and preferentially oriented in the (002) crystallographic direction. The AZO thin films, which were deposited at $T=300^{circ}C$ for 10 mTorr, shows the highest (002) orientation, and the full width at half maximum (FWHM) of the (002) diffraction peak is $0.42^{circ}$. The lowest resistivity ($2.64{ imes}10^{-3};{Omega}cm$) with the highest cartier concentration ($5.29{ imes}10^{20};cm^{-3}$) and a Hall mobility of ($6.23;cm^2/Vs$) are obtained in the AZO thin films deposited at $T=300^{circ}C$ for 10 mTorr. The optical transmittance in the visible region is approximately 80%, regardless of process conditions. The optical band-gap depends on the Al doping level as the substrate temperature increases and the working pressure decrease. The optical band-gap widening is proportional to cartier concentration due to the Burstein-Moss effect.