Abstract: Gold nanostructures exhibit promising potential in solar photocatalysis due to their localized surface plasmon resonance and excellent chemical stability. However, precise control over their morphology, optimization of heterostructure design, and understanding of performance enhancement mechanisms remain key challenges. This study systematically investigates the morphological regulation of gold nanoparticles, design principles of gold-based heterostructures, and their photocatalytic enhancement mechanisms. It outlines progress in core applications such as photocatalytic water splitting for hydrogen production, CO₂ reduction, organic reactions, and pollutant degradation, providing theoretical insights for developing efficient solar energy conversion materials. Three main synthesis methods, seed-mediated growth, templating, and electrochemical approaches, are summarized, focusing on how process parameters control the size, morphology, and microstructure of gold nanoparticles. Strategies and functional characteristics of gold-based heterostructures, including gold-noble metal, gold-silica, and gold-semiconductor composites, are reviewed. Applications and performance enhancement mechanisms in photocatalytic hydrogen production, CO₂ reduction, organic reactions, and pollutant degradation are emphasized. Results show that seed-mediated growth allows precise anisotropic control through capping agents, precursors, and reducing agents. Templating produces uniform and morphologically complex gold nanostructures, while electrochemical methods enable in situ controllable synthesis via potential and time adjustment. Gold-based heterostructures integrate plasmonic properties, interfacial charge separation, and catalytic activity, significantly broadening functionality. The localized surface plasmon resonance of gold nanoparticles extends light absorption, suppresses charge recombination, and leads to high photocatalytic activity, closely related to particle size, morphology, heterostructure type, and interfacial coupling. This work provides systematic theoretical guidance for the controlled synthesis, structural design, and photocatalytic application of gold nanomaterials.