The tribological behavior of PEEK composites reinforced with various amount of potassium titanate whisker (PTW) and carbon fibers (CF) in alkaline solutions were investigated separately.The related mechanisms were discussed based on the SEM examination of worn surfaces and transfer behavior.The results indicate that under dry condition the wear resistance of 15%(mass) PTW reinforced PTFE/PEEK composites is 10.5 times that of 15% CF reinforced composites.In alkaline solutions，CF increases the friction coefficient and wear rate of PTFE/PEEK composites and decreases their wear resistance，while PTW reduces the friction coefficient and wear rate of the composites.With 5% of PTW content，the wear resistance of PTFE/PEEK composites in alkaline solutions is increased by 2.36 times as against that without PTW.The alkaline solution hinders the transfer onto the counterpart rings significantly，but PTW reinforces the wear resistance of PEEK composites owing to its tunnel crystal fiber structure and small size.On the other hand，furrow and abrasive wear are the main mechanism for CF reinforced PTFE/PEEK composites in alkaline solutions.