The efficiency of photogenerated charge transport is one of the critical factors determining the photocatalytic performance in heterostructured photocatalysts. In this work, a two-dimensional conjugated polytriazine imide (PTI)-based photocatalyst was developed to achieve fast photoexcited electron transfer. These heterostructured nanosheets were synthesized by a one-pot condensation of a precursor mixture of cyanamide and N-doped graphene quantum dots (N-GQDs) in ZnCl2 containing salt melts. The ionothermal synthetic approach results in the N-GQDs/PTI in-plane heterostructured nanosheets, loaded with well-dispersed ZnO quantum dots (ZnO-QDs). Especially, the N-GQDs are coupled with PTI through the nitrogen atoms at the edge of triazine rings, forming new pi-p-pi conjugated connection units. Therefore, the obtained ternary heterostructured nanosheets can synchronously promote photoelectron transport through the new pi-p-pi conjugated networks as well as extend the optical response. Importantly, it exhibits approximately 230 and 3.6 times enhancement of H-2 evolution over pure PTI and the PTI/ZnO-QDs heterostructure under visible light irradiation, respectively.