Grafing the structures in nature onto g-C3N4 is an interesting and fascinating protocol to highly optimize its performances. Herein, a novel opened-up fish-scale structured g-C3N4 nanosheet has been synthesized via a simple one-step solvothermal method for photocatalytic hydrogen evolution. The unique fish-scale structure endows g-C3N4 with unusual spatial electron transfer property, which means that the photogenerated electrons selectively migrate along the flat direction to the edges of fish-scale flakes. This property well reveals the transfer path of photogenerated charges and the origin of high charge separation efficiency in photocatalytic reaction, thus yielding a remarkable catalytic activity (a hydrogen-evolution rate of 1316.35 mu mol h(-1) g(-1)), nearly 20 and 2.93 times higher than that of bulk g-C3N4 and exfoliated g-C3N4 nanosheet. Besides, the fish-scale structured g-C3N4 also owns a superior durability and stability, indicating an outstanding potential application in solar fuel production. The research results would provide a platform for the design and construction of high-performance photocatalysts with highly-efficient charge separation. (C) 2017 Published by Elsevier B.V.