This study first compares the differences in protein expression profiles of small intestine tissues between RE rats and control rats using high-throughput proteomics technology. A total of 20 male Sprague-Dawley rats are randomly divided into two groups: the control group and the radiation group, with 10 rats in each group. The radiation group is subjected to the previously established RE model, receiving a single 10 Gy dose of 6MV X-ray irradiation at a dose rate of 220 cGy/min, with a source-to-skin distance of 100 cm (Fig.2). The experimental protocol has been approved by the Animal Experimentation Committee of the Northern Theater General Hospital, with approval number 2024-56 from the Animal Medical Research Ethics Subcommittee, dated August 28, 2024. During the design and implementation phases, we strictly adhered to the "3Rs" principle. At 72 hours post-irradiation, rats are euthanized and small intestine tissue samples are collected. The tissues are fixed, dehydrated, and embedded in paraffin, then sectioned into 5 μm thick slices for HE staining. The staining procedure involves hematoxylin staining for 5-10 minutes, eosin staining for 1-2 minutes, followed by dehydration, clearing, and mounting. Total protein was extracted from small intestine tissues and analyzed using TMT labeling quantitative proteomics technology. After processing, the samples were labeled with TMT reagents and separated and detected using the EASY-nLC™ 1200 nanoflow UHPLC system and Orbitrap Exploris 480 mass spectrometer (equipped with FAIMS). The mass spectrometry parameters were set to a resolution of 60,000 for MS1 and 30,000 for MS2 (at 200 m/z) to ensure high-quality data acquisition. All experiments were performed in triplicate to ensure the reliability of the results. The raw mass spectrometry data were processed using Proteome Discoverer software (version 2.4, Thermo Fisher Scientific) and searched against the Uniprot database (rattus_norvegicus_uniprot_2021_7_15. fasta, containing 36,213 sequences) using the Sequest HT search engine. Differential expression analysis was conducted with Fold Change (FC) ≥2.0 for upregulated proteins and FC ≤0.50 for downregulated proteins, with a significance level of p<0.05. This workflow enabled accurate identification and quantification of proteins in the samples and allowed us to pinpoint proteins with significant differential expression under different conditions