The modification of graphitic carbon nitride (g-C3N4) for visible-light photocatalytic water splitting is a very hot topic due to the more and more serious energy and environment problems. Here we report a novel, general and cost-effective approach via Schiff base chemistry to construct aromatics-grafted g-C3N4-based copolymers. Based on this general strategy, almost all kinds of aromatics can be grafted into carbon nitride networks. As-synthesized copolymers all show remarkably enhanced and stable visible-light photocatalytic hydrogen evolution performance. In addition, the low cost and small optimized adding amounts of these co-monomers adopted here make the present strategy probably the one of most cost-effective copolymerization approach to construct g-C3N4-based copolymer photocatalysts.