The invention relates to the technical field of valve sealing materials, in particular to a valve sealing nano-carbon fiber modified polytetrafluoroethylene composite material which comprises polytetrafluoroethylene, nano-carbon fibers, diatomite, quartz sand, white carbon black, linear phenolic resin, dibutyl phthalate, p-phenylenediamine, phenyl salicylate, self-cleaning agents, flame retardants, glycerol, paraffin and absolute alcohol. The polytetrafluoroethylene is modified by the nano-carbon fibers, the prepared composite material has the advantages of good plasticity, high-temperature resistance, aging resistance and corrosion resistance, can be machined into various shapes and is low in friction coefficient. The self-cleaning agents in raw materials comprise titanium dioxide and titanium phosphate, the titanium dioxide can absorb light with a certain wavelength and generate free electrons and holes, pollutants adsorbed on the surface of a film are oxidized, reduced and decomposed to remove and kill surface micro-bacteria, so that the self-cleaning agents have a self-cleaning function, and the titanium phosphate can achieve self-cleaning effects only by the aid of water and air without light.