This work studies aluminum doped zinc oxide (AZO) films prepared by in line sputtering. In line sputtering is a popular thin film producing method for large area and high throughput production in industry application. Different substrate heating temperatures and process gas during sputtering were applied to produce AZO films on glass with in line sputtering AZO target. Average optical transmittance 91% between 400 and 1100 nm wavelength region and electrical resistivity 6.22×10-4Ω-cm of AZO films can be obtained with pure argon process gas and 450C substrate heating temperature. Average optical transmittance 92% between 400 and 1100 nm wavelength region and electrical resistivity 4.81×10-4Ω-cm of AZO films can be also produced from argon mixed with 5% hydrogen process gas and 450C substrate heating temperature. Adding hydrogen during sputtering can increase film’s electrical conductivity. The carrier concentration for AZO films prepared from argon mixed with 5% hydrogen process gas is higher than that prepared from pure argon gas about 2.2 times when the electrical property was measured within one day after films production. The electrical property for AZO films produced from hydrogen mixture gas is unstable. The carrier concentration decreases more than one time for films produced from argon/hydrogen mixture after storing 30 days. The films produced from pure argon gas do not have this decreasing behavior. This work contributes to industry like thin film solar cell in selecting process recipe for producing AZO films as transparent electrodes.