Heteroatom-doping is an efficient approach to extend optical absorption beyond 460 nm, which, however, often reduces crystallinity to cause a concomitant detrimental effect on photocatalytic activity. In the present study, we developed a facile approach to synthesize S-doped g-C3N4 with a high crystallinity by self-assembling melamine and tri-thiocyanuric acid, followed by calcination. The resultant optimal S-doped carbon nitride (MTCN6) exhibited a super-high H-2-generation rate of 1511.2 mu molg(-1)h(-1) (about 11 times higher than that of the pristine CN) under visible light excitation (lambda > 420 nm) and an excellent AQE of 3.9% at 420 nm.