Abstract: Commercial micro-M_os₂, M_os₂nano-balls and polyacetal (POM)/M_os₂ intercalation compound (POM/M_os₂-IC) were used as fillers in polyacetal-based composites separately. The composites were selected as rubbing surface layers of self-lubrication bearing material. The micro-tribological behaviors of the composites were investigated on a Universal Surface Tester. The results showed that the intercalation of POM led to a transformation from 1T-M_os₂ to 2H-M_os₂, and as a consequence, the micro-tribological behavior of POM/M_os₂-IC was poor. POM/M_os₂nano-balls composites exhibited better micro-tribological properties than that of POM/micro-M_os₂ composites. The excellent micro-tribological performance of POM/M_os₂ nano-balls composites was ascribed to the good chemical stability, exfoliation and transfer of M_os₂ nano-balls.