BackgroundActin Alpha 2 (ACTA2) is expressed in intestinal smooth muscle cells (iSMCs) and is associated with contractility. Hirschsprung disease (HSCR), one of the most common digested tract malformations, shows peristaltic dysfunction and spasm smooth muscles. The arrangement of the circular and longitudinal smooth muscle (SM) of the aganglionic segments is disorganized. Does ACTA2, as a marker of iSMCs, exhibit abnormal expression in aganglionic segments? Does the ACTA2 expression level affect the contraction function of iSMCs? What are the spatiotemporal expression trends of ACTA2 during different developmental stages of the colon?MethodsImmunohistochemical staining was used to detect the expression of ACTA2 in iSMCs of children with HSCR andEdnrb−/−mice, and the small interfering RNAs (siRNAs) knockdown technique was employed to investigate howActa2affected the systolic function of iSMCs. Additionally,Ednrb−/−mice were used to explore the changes in the expression level of iSMCs ACTA2 at different developmental stages.ResultsThe expression of ACTA2 is higher in circular SM in the aganglionic segments of HSCR patients andEdnrb−/−mice than in normal control children and mice. Down regulation ofActa2weakens the contraction ability of intestinal smooth muscle cells. Abnormally elevated expression of ACTA2 of circular smooth muscle occurs since embryonic day 15.5 (E15.5d) in aganglionic segments ofEdnrb−/−mice.ConclusionsAbnormally elevated expression of ACTA2 in the circular SM leads to hyperactive contraction, which may cause the spasm of aganglionic segments in HSCR.Supplementary InformationThe online version contains supplementary material available at 10.1007/s00383-023-05479-x.