Mesoporous g-C3N4/g-C3N4 (Meso-g-C3N4/g-C3N4) nanosheets laminated homojunctions have been fabricated via template-calcination strategy using melamine and amino cyanamide as co-precursors. The prepared Meso-g-C3N4/g-C3N4 nanosheets laminated homojunctions possess relative high surface area of 34 m2 g−1, large pore size of 15.0 nm and narrow band gap of 2.75 eV. The visible-light-driven photocatalytic reaction rate constant of methyl orange and hydrogen production rate (∼115.6 μmol h−1 g−1) for Meso-g-C3N4/g-C3N4 nanosheets laminated homojunctions is about 12.5 and 6.5 times higher than that of the pristine g-C3N4, respectively. This may be attributed to the synergetic effect of the close-contact laminated structure contributing to the separation of photogenerated charge carriers and mesoporous structure facilitating the diffusion of reactants and products, and offering more surface active sites. This novel laminated homojunction may open up a new avenue for designing other high-efficient photocatalysts.