Graphited carbon nitride materials (g-C3N4) with high visble-light response were synthesized by thermal condensation of melamine at varied temperature. The microstructure and optical property of as- achieved catalysts were investigated by XRD, SEM and UV-Vis techniques, respectively. Moreover, rhodamine B solution was applied to measure the catalytical performance under the irradiation of different sources of light. The results showed that the major structures of g-C3N4 were kept, though lots of blocks were scattered on the surface because of the damage of lamellar structure caused by the high temperature. As the thermal temperature was increased, the adsorptions of light were greatly enhanced in both UV and Vis region, which might be due to the decrease in reflection and the increase in refraction at the lumpy surface. In the degradation of rhodamine B solution, all the samples showed high photocatalytic activities under the irradiation of both visible-light and sunlight, and 94.8% (60min, under Vis-light) and 91.1% (90min, under sunlight) of RhB were degraded when the thermal temperature was 580℃. This research would greatly enlighten the studies of environmental purification using clean green energy.