Abstract: The determination principle of the vitrinite maximum reflectivity and macerals is elaborated, details of test instruments, the use of materials required, sample preparation and measurement conditions are provided. Research shows that No.13 coal seam is gas-fat coal, macerals and vitrinite maximum reflectivity of the different layers are measured, vitrinite, inertinite, liptinite and mineral composition of differernt layers are presented. The conclusion shows that the extraction process may have harmful gases such as H₂S and spontaneous combustion danger, and the coal seam water and fire-fighting should be strengthened.