The basalt fiber with fiber diameter 5.5um was prepared by initial twisting and retwisting, and then treated by organic matter tetrafluoride coating. The treated yarn is smoother, softer and wear-resistant. With temperature resistance(to 800ºC), chemical corrosion resistance, high strength characteristics, in the high-speed industrial sewing thread does not produce untwist phenomenon, in the sewing process does not raise hair, continuous thread.