In this work we report the feasible modification of graphitic carbon nitride (g-C₃N₄) polymer through a postfunctionalization progress.The resultant photocatalyst exhibits boron doping and mesoporous structure with a high surface area of 125 m2/g,leading in an increased surface activity for photocatalytic water splitting reaction.X-ray diffraction,X-ray photoelectron spectroscopy,PL emission spectra and UV-Vis spectra were used to detect the properties of as-prepared samples.Based on X-ray photoelectron spectroscopy analysis,boron is proposed to dope in the g-C₃N₄ lattice.Optical studies indicated that boron doped g-C₃N₄ exhibits enhanced and extended light absorbance in the visible-light region and a much lower intensity of PL emission spectra compared to pure g-C₃N₄.As a result,boron doped g-C₃N₄ shows activity of 10.2 times higher than the pristine g-C₃N₄ for photocatalytic hydrogen evolution.This work may provide a way to design efficient and mesoporous photocatalysts through post modification.