Graphdiyne (GDY) has been widely applied in the field of photocatalytic hydrogen production due to its unique chemical structure and excellent photoelectric performance. In this study, CuBr was used as a catalytic substrate to prepare CuBr/GDY through a cross‐coupling reaction, and a novel NENU‐5/CuBr/GDY tandem S‐scheme heterojunction photocatalyst was constructed at low temperature. The NENU‐5/CuBr/GDY heterojunction exhibited significantly enhanced activity in photocatalytic hydrogen evolution, with hydrogen evolution reaching 226.62 μmol in 5 h, which was 4.7 and 12.6 times greater than that of pure GDY and NENU‐5, respectively. Comprehensive evaluation of electrochemical, photoluminescence, and time‐resolved photoluminescence indicated that the enhanced activity of the NENU‐5/CuBr/GDY composite catalyst was attributed to high photocurrent response and low electrical resistance, which increased the efficiency of photogenerated charge separation. Additionally, density functional theory (DFT) calculations and work function proposed the possibility of constructing the NENU‐5/CuBr/GDY tandem S‐scheme heterojunction structure. In summary, this work provides valuable ideas into tandem heterojunctions for photocatalytic hydrogen production.This article is protected by copyright. All rights reserved.