Abstract: The corrosion resistances of three kinds of fluorine rubber O-rings in acid medium were evaluated comprehensively through studying the physical dimensions, mechanical properties and morphology changes of the O-rings in free and compressive stress state before and after corrosion. The results show that after corrosion the tensile strength, elongation at break and hardness of the fluorine rubber O-ring decreased and the physical dimension changed. The corrosion degree of the O-ring was weaker in the compressive stress state than in the free state; in the compressive stress state, the liquid corrosion was weaker than the gaseous corrosion, but it was on the contrary in the free state. After corrosion, plastic deformation, local bubble, or even crack occurred in the O-rings.