The invention discloses a polytetrafluoroethylene composite material, which comprises one or more of molybdenum disulfide, aluminum sesquioxide, copper powder, graphite, silicon dioxide and stainless steel powder and polytetrafluoroethylene, wherein the polytetrafluoroethylene composite material is a binary polytetrafluoroethylene composite material, which comprises 80 to 99.9 weight percent of the polytetrafluoroethylene, and the balance of other components. A product preparation method for the material comprises the following steps: compounding the materials of polytetrafluoroethylene (PTFE), molybdenum disulfide (MoS2), aluminium oxide (Al2O3), Cu powder, silicon dioxide (SiO2), polyphenylester (PPL), stainless steel powder, carbon fiber (CF), glass fiber (GF) and the like, molding the materials by a mold pressing sintering method, and then mechanically machining the materials to form an L-shaped sealing element.