Autism spectrum disorder (ASD) involves complex genetic-environmental interactions, with the gut microbiota (GM)-brain axis playing a key role. To explore whether the ASD risk gene Cntn4 contributes to disease development via gut-brain connectivity, our study employed a Cntn4 knockout mouse model. The microbial diversity and abundance in the gut contents of these mice were assessed using 16S rDNA sequencing, while metabolite changes in the gut contents, serum, and cerebral cortex were detected via metabolomics methods. The results showed that Cntn4 gene knockdown induced autism-like behavioral changes and accelerated gut transit in mice. Compared with the control group, significant differences were observed in the composition of the GM and metabolomics profiles. Notably, alterations in GM (e.g., Adlercreutzia, Desulfovibrionaceae_unclassified) and disruptions in several metabolic pathways, including arginine-proline, histidine, sphingoid, tyrosine, and purine metabolism, were identified. Multi-omics analyses linked microbial shifts to metabolite changes in the gut contents, serum and cerebral cortex, particularly organic acids. These findings suggest that knockout of the Cntn4 gene may lead to autism-like changes in mice through mechanisms associated with alterations in GM and gut-brain axis metabolites. This study provides valuable insights into the mechanisms underlying ASD development and offers potential directions for the prevention and treatment of ASD.