Adopting the eccentric multi-level metal hard sealed structure, the pneumatic eccentric shut off butterfly valve has no mechanical wear, can reach to zero leakage, possess excellent two-way sealing function, so it is the best device used in petroleum industry, chemical industry, metallurgy industry, electricity, food industry, medicine, water supply and drainage, pipeline for gas delivery with different media for controlling flow, cutting off or connecting the fluid. After adopting different materials, it can be suitable for different media, such as water, sewage, sea water, air, steam, coal gas, flammable gas, corrosive media, oil and food products and other media.