Abstract: Appearance of bubbles in PL-220 high temperature gel permeation chromatography was described. Its effects on the instrument and experimentation were discussed. With these bubbles, the instrument running state became unstable and baseline took on serrated fluctuation. Many reasons could induce the bubbles, such as pipeline leaking, valves slop, and manipulation error. These reasons were analyzed one by one. It was decompose of solvent which resulted in the appearance of bubbles. Many methods could be adopted to avoid or resolve this problem. The instrument should keep idle on small flow rate and lower temperature such as 40℃, a temperature higher than room temperature no more than 20℃. Replacing the circumfluence solvent with antioxidant periodically and keep it fresh.