The suggested mechanism of photocatalytic oxidization of EM over Cu2O@H2Ti3O7 nanocomposite under sunlight irradiation. Under the sunlight irradiation, photo-generated electrons (e?) of nanocomposite aggregated on nanotubes, and holes (h?) aggregated on Cu2O nanoparticles, which will reduce the bandgap energy and prolong the effective separation of photo-induced electron-hole pairs, enhance eventually the photocatalytic activity. It causes a large number of the hydroxy radical groups (·OH) generated on nanocomposite, which will effectively oxidize EM due to the synergistic effect between them to form heterojunction structure. Therefore, nanocomposite exhibits the excellent photocatalytic performance.