A nanoporous ternary polymer sheets with enhanced photocatalytic activity on H-2 evolution from water was prepared by a simple one-pot template-free polymerization in the absence of any catalyst, which was linked by aminal and imine bonds through condensation of melamine (M) and p-phenylenediamine (P) with terephthaldehyde (T). In comparison with binary condensation of M and T, the introduction of P can improve the structural crystallinity, conjugation and regularity of terpolymer by forming imine bonds, thus enhancing visible light absorption and separation of photogenerated electron-holes. Therefore, the terpolymer sheets prepared by simply practical route and cheap raw materials showed high photocatalytic capacity with 74.81 mu mol average H2 evolution rate from water under UV-vis light (lambda > 350 nm) without help of any co-catalyst, which is about 4 times of optimized bipolymer (18.56 pistol h(-1)) and about 8 times of graphite-like carbon nitride polymer (pure bulk g-C3N4, 9.43 pmol h(-1)). The internal heterojunction in terpolymer formed by co-existence of aminal and imine blocks perhaps played a similar role as the hybrid of two kinds of semiconductors to promote electron-hole separation. The various linkages between monomers in the polymeric network can provide different functional possibilities, which would expand a new approach to design polymeric photocatalysts.