Abstract: Polycyclotriphosphazene-sulfone (PCPS) microsphere synthesized with hexachlorocyclotriphosphazene as raw material was used to prepare epoxy resin composite coatings by air spraying on the surface of steel sheets. Structures of PCPS microsphere and composite coatings were analyzed by XRD and SEM, and the effects of microsphere content on the tribological properties of composite coatings were investigated on a friction and wear tester. Results show that PCPS microsphere with 493 nm average diameter had amorphous structure and could well disperse in coatings. The friction coefficient and wear loss of composite coatings first decreased and then increased with the increase of microsphere content, and the composite coating with 3 wt.% content of PCPS microsphere exhibited the lowest friction coefficient of 0.37 and the smallest wear loss of 1.8×10-6 mm3. Adhesive wear mechanism played a dominant role during wear process.