Abstract: The ultra-thick gallium-doped zinc oxide(GZO) films were deposited at room temperature by DC magnetron sputtering of a lab-made GZO target on alumina crystals substrate to improve the stability of GZO film properties. The effects of different sputtering power of GZO films were investigated while the argon flow rate was 40sccm, the sputtering pressure was 0.2 Pa, the target distance was 100 mm and the sputtering time was 30 minutes.The GZO films were characterized with X-ray diffraction, four –probe tester, atomic force microscope and ultraviolet visible near infrared spectroscopy. The results show that the grain size of the GZO film gradually increases and the growth direction of the unit cell changes from radial growth to lateral growth with the increase in sputtering power. When the sputtering power increases, the average light transmittance of the film in the visible light range increases first, then decreases, and finally increases again. The sheet resistance of the GZO film samples gradually shows a downward trend with the increase of power. When the sputtering power is 250 W that the minimum sheet resistance of the film is 18 Ω/□. In the case of the sputtering power being 180 W, the preferred orientation diffraction peak of the film reaches the maximum, the unit cell growth of the film is full and the crystalline properties of the film are superior. The average light transmittance of the GZO film reaches the highest in the visible wavelength range and the sheet resistance of the film is 34 Ω/□.