Abstract: This study aimed to prepare highly viscous and easily gelling pectin through enzymatic amidation modification and investigate the effects of amidation on the physicochemical properties of pectin. With papain as the catalyst, phenylalanine was grafted onto pectin molecules, and analytical techniques including ¹H NMR, FTIR, and XPS were employed to characterize the structure of the modified pectin while simultaneously evaluating its viscosity, gelling performance, and rheological properties. The results demonstrated that phenylalanine was successfully grafted onto the pectin molecules via amide bonds, with a grafting rate of 32.01%. FTIR and XPS analyses further confirmed the formation of amide bonds and their chemical structure. Compared to native pectin, the amidated modified pectin exhibited substantially enhanced viscosity, reaching up to 20 times that of the native pectin, along with markedly improved gel strength and elasticity. Microscopic morphology observations revealed that the modified pectin formed a more uniform and compact three-dimensional network structure, with optimal network integrity at pH 3. Rheological tests confirmed that the storage modulus and loss modulus of the modified pectin were higher than those of the native pectin, indicating that amidation modification enhanced intermolecular interactions and improved network stability, enabling the pectin to display excellent physicochemical properties under acidic conditions. This research provides new insights for expanding the application of pectin in food, pharmaceutical, and other fields.