Polyaryl ether sulfone/polymethylphenlsiloxane (PES/PMPS) microcapsules were prepared and added to a polytetrafluoroethylene (PTFE)/aramid fiber composite liner for the first time to improve the tribological properties of self-lubricating fiber liners under high-temperature environments. Compared with the virgin liner, the friction coefficient and wear rate of the liner containing 9   wt.% PES/PMPS microcapsules are reduced by 48.5% and 21.6%, respectively. At the microscopic and atomic scale, lubricant PMPS changes the interaction energy between PTFE and the Fe layer to weaken the adhesion of PTFE to the friction couple, further reducing the adhesive wear of the liner. Under the action of lubricating phases PMPS and PTFE, the tribological properties of the liner are significantly improved.