Light microscopy ,immunohistochemistry, ELISA and RT-PCR were used to explore the mechanism and regulated methods of small intestine mucosal immunity dysfunction in mice after 8Gy irradiation of ,60,Co γ-rays. Results show that the irradiation could directly injure intestine lymphocytes and inhibit the IL-4 mRNA expression of mesenteric lymphocytes, with the numbers of IgA secreting plasma cells and the quantity of mucous sIgA in the intestine being significantly reduced. It has been found that rhIL-4 could increase the number of IgA-secreting plasma cells in the lamina propria and quantity of mucous sIgA. This suggests that rhIL-4 could be of help for recovery of the function of intestinal mucosal immunity.