ObjectiveTo research the mechanism underlying the effect of raw and processed Aurantii Fructus Immaturus switched to Zhishi Shaoyaosan （ZSS） on constipation-predominant irritable bowel syndrome （C-IBS） rats via the brain-gut-microbiota axis. MethodEighty rats were randomly divided into the blank， model， positive drug （pinaverium bromide， 15.625 mg·kg^-1）， raw ZSS， stir-fried ZSS， bran-fried ZSS， charcoal-fried ZSS and finished ZSS groups （3.75 g·kg^-1）， with 10 rats in each group. Except for the blank group， which received intragastric administration of 0.9% sodium chloride solution at room temperature， all other groups were administered the ice solution at 0 to 4 ℃ （2 mL·d^-1， for a total of 14 d） to establish the C-IBS rat model. The fecal water content and the propulsion rate of small intestine were detected after 14 d of continuous drug administration. The levels of 5-hydroxytryptamine （5-HT）， vasoactive intestinal peptide （VIP）， neuro-peptide Y （NPY）， calcitonin gene-related peptide （CGRP）， substance P （SP）， diamine oxidase （DAO） and D-lactic acid （D-LA） were detected by enzyme linked immunosorbent assay （ELISA）. Hematoxylin-eosin （HE） staining was used to observe the changes in colonic pathological injury in each group. The expression levels of cyclic adenosine monophosphate （cAMP）， protein kinase A （PKA） and aquaporin-3 （AQP3） mRNA in colon tissues were detected by Real-time fluorescence quantitative polymerase chain reaction （Real-time PCR） and the protein expressions of VIP and AQP3 in colon tissues were detected by Western blot. The content of short chain fatty acids （SCFAs） was determined by gas chromatography-mass spectrometry. ResultCompared with the blank group， the fecal water content and intestinal propulsion rate of rat in the model group were significantly decreased （P<0.01）， and the levels of 5-HT， VIP， CGRP and SP in serum were significantly increased. Simultaneously， the NPY levels significantly decreased （P<0.01）， the levels of DAO and D-LA in plasma were significantly increased （P<0.01）， and the mucosal epithelium of colon tissue was slightly damaged， with reduced goblet cells and significantly reduced luminal granules. The mRNA expression levels of AQP3， cAMP and PKA and the protein expression levels of AQP3 and VIP in colon tissue were significantly decreased （P<0.05， P<0.01）. The total amount of SCFAs in feces showed an obvious decreasing trend， with the contents of acetic acid， isobutyric acid， isovaleric acid， valeric acid and caproic acid decreased significantly， while the contents of propionic acid and butyric acid increased significantly （P<0.05， P<0.01）. Compared with the model group， the treatment groups increased the intestinal propulsion rate， improved the intestinal mucosal barrier function， and adjusted the level of serum brain-gut peptide in C-IBS rats （P<0.05， P<0.01）. The expression levels of AQP3， cAMP， PKA mRNA and VIP， AQP3 protein in colon tissue of rats in all treatment groups were increased. All the treatment groups had a significant downregulation of the content of SCFAs except for isobutyric acid in rat feces， and the effect of ZSS prepared by the bran-fried Aurantii Fructus Immaturus was superior than that of other ZSS. ConclusionThe raw and processed Aurantii Fructus Immaturus switched to ZSS could influence the brain-gut-microbiota axis to treat C-IBS rats and it is more reasonable to use bran-fried Aurantii Fructus Immaturus in ZSS.