Objective: To study the effects of Lactobacillus Plantarum cell wall peptidoglycan (LPG) microspheres on mouse intestinal flora changes, peptidoglycan recognitions protein (PGRP) and cytokines expression levels. Method: Plate counting was used for enumeration of the intestinal flora. Real-time PCR was used for quantification PGRP in different tissues. Cytokines content were determined by ELISA kits. Result: The mouse administered orally with LPG microspheres showed significantly higher number of Lactobacillus and Bifidobacterium in caecum contents (p<0.01). The amount of PGRP expression in different organs was highest in LPG microspheres-treated group. IL-4, 12, IFN-gamma, TNF-alpha contents in serum from LPG microspheres-treated mouse were significantly higher than those in normal saline-treated group (p<0.01). Conclusions: This study shows that the LPG microspheres can regulate intestinal flora imbalance and improve systemic immunity, improve both Th1 and Th2 immune response, which provide some basis for the use of LPG as potential adjuvants.