The composite of polytetrafluoroethylene (PTFE) has been generally applied to dynamic seals in Stirling power systems due to its excellent self-lubrication and resilience. In this article, the tribological behavior of polyphenylene sulfide (PPS)-PTFE blends filled with nano-Al₂O₃ are investigated under different contact loads, sliding speed, and operating temperatures using a block-on-ring friction and wear tester. The results indicate that the addition of nano-Al₂O₃ could significantly improve the antiwear performance of the PPS-PTFE blend. Nano-Al₂O₃-filled PPS-PTFE composites have good tribological performance under high-temperature environments. When the content of nano-Al₂O₃ is 5 wt%, the wear rate of the composite is 276 times better than that of virgin PTFE and more than 150 times better than that of unfilled PPS-PTFE. Dynamic mechanical analysis (DMA) shows that the block of the movement of molecular chains of PTFE with the addition of nano-Al₂O₃ particles may be responsible for the significant decrease in the wear rate. The greatest impact on the antiwear performance of the composite for Stirling engines is load, followed by temperature, and the minimum effect is due to sliding velocity.