Liquidus temperature is an important parameter in glass manufacturing process and is essential for assessing the stability of glass formulations. Based on the gradient furnace method, the influences of thermal insulation time, sample shape and observation position on the accuracy of liquidus temperature measurement of ultra-thin alkali-free glass were explored. The results showed that the liquidus temperature of glass was more accurate when the insulation time was 24 hours, the sample form was rod, and the observation position was inside glass. This study can provide a reference for the determination of glass liquidus temperature, and then provide support for glass formula design and industrial production.