Pd nanoclusters supported on Schiff base modifying graphitic carbon nitride (Pd/u-CN100) had been successfully synthesized using urea and terephthalaldehyde as precursors by an impregnation approach. The resulting sheet materials exhibited high catalytic activity that turnover frequency rose to 98.9 h(-1) and stability in CO2 hydrogenation. Various factors affecting formate production including the addition amount of TPAL, reaction pressure, reaction temperature, and catalyst stability testing were studied to achieve favorable catalytic conversion. An amount of characterization methods were applied to investigate the structure-activity relationship, including TEM, XRD, XPS, FTIR, HETEM, EDS, and BET. The high activity and stability might be resulted from the electronic modification, the relatively high dispersion of noble metal nanoclusters and the formation of intensely anchored metal-carrier bonds. More concretely, the scattered Schiff base loci and multiple nitrogen species were of great significance in the efficient and durable CO2 hydrogenation system.