The invention discloses a polytetrafluoroethylene bidirectional dust ring. The polytetrafluoroethylene bidirectional dust ring comprises a sealing lip and an O-ring; anti-skid lines are formed on theinner surface of the sealing lip; a clamping groove is formed in the outer side of the sealing lip; the O-ring is mounted in the clamping groove; the sealing lip is prepared from the following components in parts by mass: 100-110 parts of polytetrafluoroethylene resin, 0.2-0.7 parts of calcium carbonate, 0.6-1.6 parts of calcium oxide and 0.8-3 parts of processing aids; and the O-ring is preparedfrom the following components in parts by mass: 80-100 parts of nitrile rubber, 8-15 parts of montmorillonite, 6-10 parts of PTFE ultrafine powder, 3-8 parts of carbon fiber, 0.5-3 parts of dispersantsodium dodecyl benzene sulfonate, 2-5 parts of aluminum hydroxide, 1-2 parts of vulcanizing agent DCBP, 0.5-1.2 parts of accelerator DM, 1-1.2 parts of antioxidant MB1 and 5-10 parts of plasticizer DOP. The polytetrafluoroethylene bidirectional dust ring has a dust sealing two-way effect and is suitable for dust sealing of oil cylinders, air cylinders and mechanical equipment. The sealing lip andthe O-ring which are prepared by the formulas above are matched for use, so that the polytetrafluoroethylene bidirectional dust ring is able to resist acid and alkali corrosion and high temperature,a dustproof sealing effect is ensured, and maximum bearing pressure is 16 bar.