The invention discloses a technique for covering silicon coating on the surface of polyphenylene fiber. Sodium sulfide and santochlor are taken as raw materials and then synthesized to obtain polyphenylene fiber protofilament after the melt spinning; heat drawing treatment is applied to the fiber protofilament so as to get finished fiber; after the protofilament finished fiber is precoated with film material solution which contains at least one of the components of phenol silicone resin, hydroxy-polyorganosiloxanem and PPTA, the heat treatment is carried out under the condition of normal atmosphere air of 20-360 DEG C or nitrogen protection so as to get the polyphenylene fiber products with the thickness of 1-100 micron silicon coating. The obtained polyphenylene composite fiber is especially suitable for serving as filter materials in thermal power generation, garbage incinerators, chemical filters, and the like.