ObjectiveTo explore etiopathogenesis of slow transit constipation(STC). MethodsThe model of rat with “cathartic colon” was established, and the changes of colonic electromyography of the rat was examined. ResultsThe frequency and amplitude of slow wave in vivo of rats with cathartic colon was decreased markedly. Postmeal spike potential and duration was decreased, showing that gastrocolonic reflex of rats colon was decreased.ConclusionLong term abuse of stimulant laxuatives could damage enteric nervous system and accelerate the pathological changes of STC.