Constructing Z-scheme system is a promising way to fabricate efficient photocatalysts for solar light utilization. In this study, a novel all-solid direct Z-scheme photocatalyst PTCDA-C3N4 was synthesized and characterized by several methods. XRD and HRTEM confirmed the strong pi-pi interaction between PTCDA(Perylene-3,4,9,10-tetracarboxylic dianhydride) and g-C3N4 induced the crystal transformation of PTCDA from beta-phase to alpha-phase, self-assembling and reconstructing into nanocrystalline of 5nm. UV-vis and photoelectronic measurements illustrated that the coupling of PTCDA on g-C3N4 not only dramatically broadened visible light absorption, but also accelerated the charge transfer of g-C3N4. Both the theoretical calculation and active species trapping experiments verified the Z-scheme mechanism of PTCDA-C3N4 heterostructure, which endows the hole of PTCDA-C3N4 much strong oxidizability and effective electron-hole separation, thus eight times higher activity than that of pristine g-C3N4 for benzylamine oxidation under solar driven. Our current work paves a facile way for synthesis efficient Z-scheme photocatalysts.