The Polysulfonamide fiber(PSAf) reinforced polytetrafluoroethylene (PTFE) composite was prepared by means of the special dispersing method and hot molding press technique. In this paper, the thermal and tribological properties of this composite were studied in detail. The thermal properties was studied by the thermal dimension stability and thermal decomposition property with thermal expansion coefficient instrument and thermal gravity analysis(TGA). And the characterizations showed that addition of PSA fiber resulted in an increase in dimensional stability at elevated temperature, and onset decomposition temperature were reduced slightly. The tribological behaviors of these materials were evaluated with a reciprocating friction testing machine under dry friction condition. The results showed that the friction coefficients kept at a low level, and the wear resistance of composites was effectively improved by the content of fiber. Moreover, the mechanism of wear resistance of the materials was studied by their micro-structure. The scanning electron microscope observations of the worn morphologies revealed that the PSA fiber effectively prevented the slip and fracture of PTFE molecular leaflets under friction stress. Keywords: PSAf/PTFE; thermal properties; tribological properties