The polytetrafluoroethylene (PTFE) sealing composite filled with magnetic nano Fe3O4 was prepared by a cold pressing, mechanical blending method and sintering process.The friction and wear performance of the PTFE sealing composite with different nano Fe3O4 content sliding against 45 carbon steel under dry friction condition was investigated on a MM 200 friction and wear tester, the worn surface morphologies were examined and the wear mechanism was analyzed with the help of scanning electron microscope. The results show that along with the increasing of nano Fe3O4 content, the hardness and friction and wear performance of the sealing composite is obviously improved, whereas the friction coefficient is first increased then decreased and again increased. The sealing composite with 15% nano Fe3O4 has the lowest friction coefficient，its volume wear rate is reduced by two orders of magnitude compared with pure PTFE. With the increase of nano Fe3O4content, the wear mechanism is transformed from the adhesive wear of pure PTFE into the combination of adhesive wear and abrasive wear.