The occurrence carbonaceous material in the Wenchuan earthquake (Mw 7.9) fault zone is divided into five different types, including: 1) initial occurrence in fault breccias; 2) angular fragments dispersed in the fault gouges; 3) carbonaceous material veins along the fault planes; 4) cataclastic carbonaceous material veins; 5) graphite in the principle slip zones of earthquakes. The carbonaceous material with a δ13C value ranging from -26.6～-23.4‰, experiencing lower than 250℃ metamorphism or zeolite to prehnitepumpellyite grade metamorphism, as well as the preserved sedimentary sequence in fault breccias suggest that the carbonaceous material in the Wenchuan earthquake fault zone originates from the wall rocks, the upper Triassic Xujiahe Formation. The formational mechanisms of each type of occurrence: 1) Initial occurrence in fault breccias formed by diagenesis; 2) Dispersed angular carbonaceous material fragments formed by mechanical damage; 3) Carbonaceous material veins are smears of carbonaceous layers in wall rocks, such as coal seams; 4) Carbonaceous material veins with cataclastic fabrics formed during seismic event and were injected into fractures driven by high pore pressure; 5) Graphite formed by graphitization of carbonaceous materialdue to frictional heating. Carbonaceous material reveals information of the coseismic processes of the Wenchuan earthquake fault zone. 1) The coseismic slip as well as the frictional heat anomaly is highly localized in a quite localized range (mm or smaller order) along the principle slip zone, as most of carbonaceous material in the fault gouge has not recorded obvious frictional heating. 2) Microstructural study reflects that the carbonaceous material of low degree order doesn't weaken the fault. 3) Considering the Wenchuan earthquake fault cuts through different thick hydrocarbon source rock layers, the enrichment carbonaceous material and weakening by graphite are likely very common in the Wenchuan earthquake fault zone shallower than 10 km.