The two-dimensional graphitic carbon nitride (2D g-C3N4) shows excellent photocatalytic performance due to its graphene-like structure, unique electronic and optical property. However, the 2D g-C3N4 suffers from lower visible light utilization because of the quantum size effect. Herein, a new approach was developed to prepare the surface nitrogen modified 2D g-C3N4 nanosheets (NCNS) through a facile hydrothermal treatment route. The asobtained NCNS exhibited a high hydrogen evolution rate of 19.8 mmol h(-1)g(-1) with a turnover number (TON) of 642.39 in 5 h, and the external quantum efficiency (EQE) of 10.7% at 420 nm was superior to the g-C3N4 different morphological regulation. The surface nitrogen modification prompted electron delocalization of two-dimensional electron system, leading to accelerating photon-generated carrier separation and transportation efficiency.