Graphic carbon nitride (g-C3N4) is a kind of promising organic semiconductor in visible light driven photo-catalysis due to its metal free, high physicochemical stability and appealing electronic band structure. In this work, a porous hexagonal-prism g-C3N4 (ACNH) photocatalyst was successfully synthesized via an acetic acid-assisted supramolecular assembly approach followed by calcination. The resulting ACNH materials have a corrugated and closely packed porous structure, which is composed of thin layers about 30 nm in thickness. The specific surface area of ACNH is as high as 67.7 m(2)g(-1), which is approximately 8-fold of bulk g-C3N4. Moreover, the porous structure induces the red shift of the absorption edge and facilitates the photo-induced charge separation of g-C3N4. Compared to bulk g-C3N4, the ACNH sample exhibits almost 13-fold improvement for the RhB degradation with the rate constant of 0.053 min(-1). This finding suggests that the acid-assisted supramolecular assembly may become a feasible method to synthesize g-C3N4-based photocatalysts with higher surface area and photocatalytic activity.