Abstract: This paper discussed the relationship between coal caracteristics and enclosing lithologies of coal seams from French Lorrain coal basin.Coal quality degradation and vitrinite reflectance increase were found in coal seams enclosed or overlain by sandstones.The reasons for the quality degradation were due to the weak reductibility during coal seams deposition and the abundance of inertinite in these coals.oxidation of these coals raised the reflectance of their vitrinite.