Abstract: In order to ensure roof stability at different areas,applying drilling core,microstructure observation by rock slice and taking ratio of sand to mud as main index on the basis of coal and rock sedimentology,roof stability was classified into 5 degrees from Ⅰ~Ⅴ.Results showed that ratio of sand to mud might be as important basis of roof stability classification after it was standardized.Thus mine roof stability classification map was obtained.In test mine,roof sandstone strength was low,rock strength reduced in wet drilling and anchored quality could not meet design requirement.Main reason included that the ratio of sand to mud was low,mudstone content was large,roof stability of most areas was between Ⅲ~Ⅴ.In designing Ⅳ and Ⅴ degree roof supporting parameters,supporting structure instability because of rock strength decrease should be monitored especially.