The etiology and pathogenesis of functional constipation in children Functional constipation (FC) refers to constipation caused by organic diseases of the external intestinal tract or systemic organs and medication factors, and the incidence rate accounts for 90%~95% of children’s constipation. The etiology and pathogenesis of FC are still unclear, and this article summarizes the common etiology and pathogenesis of FC. Dietary factors Lack of adequate dietary intake, irrational dietary structure is an important factor causing constipation, lack of dietary fiber and adequate water intake are easy to cause constipation. Psychological and socio-behavioral factors Children are prone to prolonged and deliberate bowel holding for various reasons, which can lead to dilatation of the rectum and low colon, prolonged fecal retention, hard and dry stools, and fecal impaction, thus leading to constipation. On the other hand, lack of good defecation habits and failure to master the correct way of defecation are common causes of constipation in infants and young children. Abnormalities of intestinal motility Abnormalities of intestinal motility include colonic dyskinesia and anorectal dyskinesia. Colonic dyskinesia is the cause of slow-transmission constipation, and the pathophysiologic mechanism is unclear. Pathologic changes in the colonic nervous system and intestinal smooth muscle are the main causes of abnormal colon dynamics.Abnormalities in the distribution and function of Cajal mesenchymal stromal cells are important factors in intestinal dynamics disorders. Rectal-anal dyskinesia manifests as outlet-obstructive constipation, with common causes such as anal sphincter incoordination and pelvic floor muscle spasm syndrome. Changes in intestinal motility-related neurotransmitters and receptors are important causes of abnormal intestinal motility. Abnormalities in the levels of gastrointestinal hormones can cause abnormalities in gastrointestinal dynamics. About 40 gastrointestinal hormones have been identified, such as gastric motility, vasoactive intestinal peptide, and 5-hydroxytryptamine. Effect of intestinal microecology The intestinal microecological environment of children with FC is different from that of the normal population, but the causal relationship between FC and changes in intestinal flora is uncertain. A favorable intestinal microecology helps to shorten colonic transit time, which may be related to the fact that probiotics decompose intestinal luminal contents to produce lactic acid and short-chain fatty acids, which can act on intestinal nerves and stimulate intestinal peristalsis, thus promoting defecation. Summary In summary, the pathogenesis of FC is associated with many factors, especially the abnormalities of intestinal dynamics and alterations in the intestinal microecological environment are increasingly emphasized in relation to FC. It is of great clinical significance to further explore the potential pathogenesis of FC and find an effective treatment pathway.