Photocatalysis is a promising technology which can be applied in the fields of energy and environment. However, low charge separation efficiency has limited its commercial applications. In this work, we report a route to a controllable synthesized visible-light-driven heterostructure photocatalyst Mo2C@C/2D g-C3N4. The interfacial conductivity was improved by introducing Mo2C@C, which promoted the transportation of photogenerated carriers and suppressed their recombination. The optimal composite achieved a hydrogen (H2) generation rate of 2269.47 μmol g-1 h-1, and an external quantum efficiency (EQE) achieved 9.07% at λ = 405 nm. Thus, the great co-catalytic activity of Mo2C@C was unambiguously demonstrated.