The novel carbon material graphdiyne (GDY) is a two-dimensional planar structure material formed by the hybridization of sp and sp2, which has abundant carbon–carbon bonds and stable semiconductor properties. In this work, CoTiO3 was coupled with a carbon material GDY to successfully construct an S-scheme GDY/CoTiO3 heterojunction. This form of heterojunction can effectively promote the separation of charge carriers and shorten the electron transfer pathn. The loading of CoTiO3 effectively enhances the charge transfer rate of GDY and increases the number of photo-generated electrons involved in the hydrogen production reaction, thereby promoting hydrogen generation. The tests results demonstrate that GDY/CoTiO3-25 achieves a hydrogen production of 123.95 μmol under visible light irradiation, which is 13 times higher compared to GDY. This work provides insights into improving the photocatalytic performance of the novel carbon material GDY.