Ultra-thin float glasses with three thicknesses were annealed at different rates to test their elasticity modulus and investigate the effect of annealing rates on the elasticity modulus of ultra-thin float glasses. The test results showed little difference in elasticity modulus values for glasses with different thickness at the same annealing rate. As the annealing rate decreased, the elasticity modulus values of the glass with the same thickness became larger. When the annealing rate decreased to a certain value, the annealing rate continued to decrease, and the modulus of elasticity modulus values remained unchanged.