To study the differentially expressed genes correlative to irradiation-induced damage in mouse intestinal tract and its repair by foreign mouse small intestinal RNA. Divide 90 mice into 4 groups randomly. For the experimental groups, each mouse was given 40,µ,g foreign mouse small intestinal RNA, and for the control groups, 0.4mL of 0.9% NaCl. The intestinal specimens were collected form each group 6h, 12h, 24h, 4d and 8d after ,60,Co γ-rays irradiation respectively. The differentially expressed genes in the tested and control groups were checked and cloned by long-distance PCR based on subtractive hybridization. 165 differential gene clones were obtained, of which 75 named as AXCZI-75 maybe were correlated with the irradiation-induced damage in mouse intestinal tract; and 90 named as XCZ1-90 maybe were correlated with repairing of the damaged mouse intestinal tract by foreign mouse small intestinal RNA.