Ball valve sealing performance should have general requirements for sealing materials, sealing ring should pay attention to the following conditions: (1) the elastic and elastic resilience; (2) appropriate mechanical strength, including tensile strength, elongation and tensile strength etc.. (3) stable performance, less swelling in medium, and little effect of thermal contraction (Joule effect). (4) easy to process, and can maintain precise size. (5) no corrosion of the contact surface, no pollution of the medium, etc..