Gold nanoparticles (AuNPs) have been widely used in various catalytic reactions due to their unique surface properties and excellent catalytic activity. However, free AuNPs tend to aggregate due to their high surface energy, which contributes to a reduction in catalytic activity. Immobilizing AuNPs on a suitable support can prevent aggregation and further enhance their catalytic performance, and is therefore considered an ideal solution.In this study, reduced graphene oxide/chitosan/gold nanoparticles (rGO/CS/AuNPs) composites were prepared using chitosan as a reducing agent and stabilizer, and their catalytic reduction performance against 4-nitrophenol (4-NP) was investigated. The preparation conditions of rGO/CS/AuNPs composites, including chitosan MW, pH, and reaction temperature and time were investigated in detail. The structure of the rGO/CS/AuNPs composite was characterized by SEM and TEM. The results show that low-molecular-weight chitosan exhibits stronger reducing capacity in the reduction of GO. At 90℃, pH = 5, with a chitosan molecular weight of 2.1×104^{Da, a highly reduced}rGO was prepared, and spherical AuNPs were uniformly dispersed on its surface. The rGO/CS/AuNPs composite demonstrated excellent catalytic performance in the catalytic reduction of 4-NP, yielding a removal rate of 98.9% and a reaction rate constant of 0.1742 min?1.