Graphdiyne (GDY), as the latest carbon material, has demonstrated exceptional performance in a number of applications. The good conduction performance of GDY may promote the electron transfer and greatly improve the low separation rate of electron–hole pairs caused by the slow electron transfer rate. Herein, CuI–GDY was obtained by the cross-coupling method, and CuI–GDY/NiMn(LDHs) composite catalysts were obtained by a simple solvothermal method. The lamellar structure of NiMn(LDHs) is endowed with a large specific surface area and a rough surface. The double S-scheme heterojunctions constructed between the composite catalysts accelerates the electron transfer rate, allowing more photogenerated electrons to participate in the hydrogen precipitation reaction. The good stability of GDY is brought to the composite catalyst after compounding and makes the hole–electron pair compounding rate of the composite catalyst decrease. Thus, the composite catalysts maintained good hydrogen precipitation activity even after 20 hours of cycling, and the hydrogen precipitation activity was further improved. The hydrogen production activity of the composite catalyst (1094.6 μmol g⁻¹ h⁻¹) was increased by 11.24, 8.80, 20.99, 3.78 and 2.58 times when compared to pure GDY, CuI–GDY, CuI, NiMn(LDHs) and NiMn(LDHs)–CuI, respectively. Furthermore, NiMn(LDHs)-x in the dye sensitization system shows strong stability. This work provides a new perspective for GDY modification on semiconductor bandgap and the application of GDY in the photocatalytic hydrogen generation reaction.