In order to study the tribological properties of carbon fiber/polyetheretherketone (CF/PEEK) composite lubricated by water under different states,a specialized experiment platform was designed,which can simulate the working conditions with different water states.The tribological properties of CF/PEEK selfmatched pairs in gaseous state,wet steam state (water vapordroplets mixed state) and liquid state of water were studied.The results indicate that gaseous state of water has no obvious lubrication effect on CF/PEEK composite,which leads to extreme frictional oscillation and high wear rate of CF/PEEK composite.The mixture of vapor and droplets of water can improve the lubrication of CF/PEEK composite in some extent,but it can not guarantee the longterm and reliable operation of CF/PEEK composite friction parts.Under the lubrication of liquid water,the CF/PEEK composite exhibits very low and stable friction coefficient,and the wear rate of CF/PEEK composite is decreased by 3 to 6 orders of magnitude compared with the wear rate under the lubrication of gaseous state of water or gas/steam mixed state of water.Based on surface morphology of worn surfaces,it is concluded that severe adhesive wear occurs under the lubrication of gaseous state and wet steam state of water,while slight abrasive wear occurs under the lubrication of liquid water.