Abstract: MoS₂ reinforced aromatic and partially alipahatic polyetherimide (PEI) films were prepared in different solvents via the two-step method，end capped by acetic anhydride and trifluoroacetic anhydride (TFAA). The thermal imidization degrees were measured by FT-IR spectrum，the thermal transitions were characterized by SDT Q600，the tribological performances were measured by M2200 tribo-tester，and the effects of molecular flexibility，end cap，proportion of MoS₂ were investigated. The effects of load and proportion of MoS₂ on μ (average value of μ during the stable friction period) were also investigated. Based on the SEM morphologies of the worn surface，the wear mechanism was determined. The result indicates that the T_g of partially aliphatic PEI greatly decreases without obvious degeneration of PEIs‘thermal stability. μ-t curve of PEI shows it s tendency：firstly fluctuates for a short period followed by a friction stable period，and lastly increases scalariformly until lubricating failure. Flexible molecular structure，end cap of TFAA and suitable proportion of MoS₂ at tribute to the better performances of the films. The 70 wt% MoS₂/PEI-2 film has the values ofμas low as 0. 027，and μ of PEI composite films varies with load and proportion of MoS₂.