Stainless steels and PEEK composites are frequently used in key friction pair of seawater hydraulic components. The stainless steel has an important influence on tribological properties of stainless steel/PEEK composite pairing. Focused on AISI 316L, AISI 630 and S32750, tribological tests were conducted under seawater lubrication. Friction coefficient and wear rate of the three kinds of stainless steels sliding against PEEK were comparatively investigated. The tribological mechanism of the friction pairs were explored through observing and measuring the worn surfaces of samples.It is shown that the average friction coefficients of the three kinds of stainless steels have little difference; compared with AISI 316L, wear resistance of S32750 and AISI 630 is admirable, and wear rate of AISI 630 is less affected by load; wear resistance of S32750 and AISI 316L is positively correlated with their hardness, while high carbon content in AISI 630 will weaken its corrosion resistance and affect its friction and wear properties in seawater.The research provides reference for selection of stainless steel material in key friction pair of seawater hydraulic components.