Functional constipation is a common bowel motility disorder that impairs patients' quality of life, but current treatments have limited efficacy. Fecal microflora transplantation (FMT) from healthy donors restores the balance of intestinal microflora and has demonstrated clinical efficacy in improving bowel movements, stool consistency and quality of life. FMT increases microbial diversity, supports beneficial bacteria and partially reconstructs the bile acid profile. It thereby modulates signaling pathways through the FXR and TGR5 receptors, which increases intestinal secretion and relieves symptoms of constipation. The gut microbiome–bile acid–receptor axis explains the link between microbiota changes and host gut motility. These mechanisms provide theoretical support for the use of FMT in functional constipation.