The invention belongs to the technical field of polytetrafluoroethylene materials and particularly relates to a filled modified polytetrafluoroethylene material as well as application and a preparation method thereof. By taking stainless steel powder as a filler, the filled modified polytetrafluoroethylene material provided by the invention is prepared from the following raw materials in percentage by weight: 70-95 percent of polytetrafluoroethylene, 3-20 percent of the stainless steel powder and 2-10 percent of molybdenum disulfide powder. The invention also provides the application of the filled modified polytetrafluoroethylene material in the aspect of preparing a sealing piece. The filled modified polytetrafluoroethylene material has good self-lubricity, wear resistance and size stability, is good in smooth finish, liable to process, excellent in corrosion resistance performance and high and low temperature resistance performance, high in mechanical strength, wide in temperature range and good in heat conductivity, is very liable to transfer heat outsides particularly under the high temperature working condition, can keep the size of a product stable without easiness in deformation, and thus the antifriction and wear resistance performance of the product are greatly improved, and the service life of the product is greatly prolonged.