The development of hydrogen energy is crucial for achieving global dual-carbon strategic goals, namely "carbon peak" and "carbon neutrality." Photocatalytic water splitting, powered by solar energy, presents a promising approach to hydrogen production. Advancing this technology requires the development of photocatalysts that are cost-effective, highly active, and stable. As a non-metallic semiconductor, g-C3N4 stands out for its potential in sustainable energy and environmental remediation technologies, garnering considerable interest for its efficiency in harnessing light-driven reactions. Although g-C3N4 exhibits promising characteristics, its practical application is significantly hindered by the rapid recombination of photogenerated charge carriers and its limited light absorption range. This review highlights various strategies employed to improve the photocatalytic hydrogen production efficiency of g-C3N4, including heteroatom doping, microstructure control, co-catalyst modification, defect engineering, and heterojunction construction. These strategies enhance active site density, light absorption capacity, and photogenerated charge separation in g-C3N4, thereby boosting electron migration rates and improving photocatalytic hydrogen production. Additionally, we explore the potential of integrating cutting-edge AI technology with advanced instrumentation for the prediction, design, preparation, and in-situ characterization of g-C3N4-based photocatalytic systems. This review aims to offer key insights into the design, development, and practical application of innovative, high-performance carbon-based catalysts.