A novel method for preparing visible light enhanced photocatalytic carbon nitride was developed by copolymerization of melamine with a nitrogen rich precursor. The synthesized carbon nitride, CN-THDTx, with a unique structure exhibits strong visible light absorption ability. XPS results confirmed that the as-prepared CN-THDTx contains abundant nitrogen in a range of 53.0-77.4 at%. Moreover, the band gap can be efficiently controlled by changing the ratio of THDT. Under visible light irradiation, CN-THDT0.15 exhibited the highest hydrogen production (2.3 times than pure g-C3N4). After twelve continuous cycling experiments for hydrogen production for 4 h and carrying out one experiment for 48 h, the photocatalytic activity of CN-THDT0.15 showed negligible change, suggesting that the prepared sample has great potential application for photocatalytic generation of hydrogen from water splitting.