Paper relics are vulnerable to conservation materials due to their fragility. To investigate the application of soy milk to conservation of paintings and paper, Xuan paper was used to simulate soy milk treated paper. T'he physical properties, degree of polymerization, surface morphology and chemical structure changes in Xuan paper were recorded. The results suggested that after soy milk treatment, there were more hydrogen bonds formed between the paper surface and soy protein, making the paper more water resistant. Treatment with soy milk resulted in a smaller change to the degree polymerization of the paper than did glue alum water. The scanning electron microscopy image shows a gel layer formed on the paper fiber surface after being treated with soy milk. This study provides information for further use of soy milk in conservation.