ObjectiveTo explore the impact of intestinal flora changes on the intestinal mucosal immunity. MethodsDenaturing gradient gel electrophoresis (DGGE) was used to study the composition of intestinal flora in three groups of laboratory mice, namely clean mice (CL mice), specific pathogen free mice (SPF mice) and conventional mice (CV mice). Immunohistochemistry (IHC) was used to study the secretion of secretory immunoglobulin A (sIgA) in these three goups of laboratory mice. ResultsThe most numerous diversity of intestinal flora was observed in the CV mice, and the sIgA secretion was also most abundant. There was a significant difference in sIgA secretion from different parts of the intestine (P<0.05), and the distribution of sIgA-positive cells in the small and large intestines was very significantly different (P＜0.01). CL mice were the second one. The intestinal flora between different parts of the intestine was not significantly different, but the distribution of sIgA-positive cells in the small and large intestines was significantly different (P<0.05). There were least strains of bacterial flora in the intestine of SPF mice, and the sIgA secretion was also least, with a non-significant difference in the distribution of sIgA-positive cells between small and large intestines (P>0.05). ConclusionsAlong with the increasing level of animal microorganism control, the diversity of intestinal microbial flora is decreased. The amount of sIgA-positive cells is positively relevant with the intestinal flora diversity. 