Novel Bi12TiO20/g-C3N4 composite was successfully prepared with Bi12TiO20 nanoparticles embedded within the fluffy crumpled g-C3N4 nanosheets. Bi12TiO20/g-C3N4 composites exhibit superior photoactivity and stability. As compared with g-C3N4 and Bi12TiO20, the photocatalytic efficiency of Bi12TiO20/g-C3N4 is effectively enhanced about 1.8- and 4.9-fold, respectively. Based on the trapping experiment, (OH)-O-center dot and O-center dot(2)- radicals are the dominant reactive oxygen species involved in the photocatalytic process. The proposed Z-scheme mechanism of charge transfer markedly promotes the carriers' migration and separation, leading to the enhanced photocatalytic performance.