The float glass was polished by acid solution (HF/H2SO4) under ultrasonic wave. The surface morphologies before and after acid etching were observed by metallographic microscope. The thickness of acid etching was measured by thickness tester, and the strength before and after acid etching was investigated via material surface and interface performance tester. The experimental conditions, such as the amount of HF and H2SO4, the temperature of acid etching and the time of acid etching were optimized under ultrasonic wave ( f =40 KHz, P=125 W) by orthogonal design test. The suitable conditions were 10% for HF, 15 min for acid etching time, 30% for H2SO4 and 25 °C for acid etching temperature, and thus the strength of float glass increased from 89.68 Mpa to 302.25 Mpa. The optimum thickness for acid etching was about 40 μm. The microscopic pictures showed that the surface defects of the glass surface such as scratch and pit weakened obviously or disappeared.