Objective In order to investigate the effects of fructus aurantii immaturus (FAI) on migrating myoelectrical complex(MMC) and its relation with substance P(SP) in rats.Methods The changes of the myoelectric activity and the content of SP in the gastrointestinal tract were examined by electrophysiology and immunohistochemical method.Results FAI increased the ratio of the active phase to the circle of MMC and the content of SP in the myenteric nerve plexus.Conclusion SP might be associated with the excitation of FAI on the gastrointestinal tract.