Commercial dye has been extensively used and released into the environment which poses potential risk to human health.As a promising way for dye degradation, photocatalysis have been researched during the past decades.Despite much progress have been made, low photocatalytic efficiency and poor utilization of sunlight still restrict further application of photocatalyst.[1] Since the year of 2009 it has been proposed to be an visible-light driven photocatalyst, graphitic carbon nitride (g-C3N4) have drawn tremendous interest due to its metal-free composition, easy preparation and visible-light response (with a bandgap of 2.7eV).Besides, 2D layer structure and tunable electronic structure make g-C3N4 a promising materials for further research.[2] Nevertheless,g-C3N4 still suffered from some drawbacks such as low visible light harvesting, small specific surface area, rapid recombination of photo-generated charge carriers and low transition efficiency.Much work have been performed such as elements doping, constructing heterojunction between g-C3N4 and other semiconductors and introducing vacancy to solve these problems.[3-5] Besides, nanostructure of g-C3N4 with high specific surface area such as nanodots, nanorods and nanosheets have been developed in recent years.However, template methods are commonly used during the process, which make the preparation complicated as well as time-consuming.Herein, we developed a simple synthesis of porous graphitic carbon nitride (pg-CN) through a hydrothermal process in the presence of ammonium hydroxide.The effect of ammonium hydroxide on the structure of pg-CN was characterized in detail by X-ray diffraction, SEM, TEM and BET.Photocatalytic activity of pg-CN was evaluated by the degradation of methylene blue (MB) under different conditions.The results show that as-prepared pg-CN exhibits a porous nanostructure composed of 2D nanosheets and interconnected pores.The photocatalytic activity of pg-CN is enhanced, owing to the synergistic effect of high specific surface area and enhanced separation efficiency of photo-generated carriers.