To observe effect of effective substances of Simotang (arecoline, linderane, hesperidin and costunolide) on gastrointestinal motility function in mice under chronic stress. Methods: 144 mice were divided into normal group (n=8) and model group (n=136).Model group was under unpredictable chronic stress, after 21d, divided to model group, Simo decoction group and 15 substances groups. 7days after medication, gastrointestinal motility were assessed. Results: The model group showed slower gastric emptying and slower intestinal propulsion compared with the normal group and the Simo decoction group (P<0.01). Three or four substance groups showed quicker gastric emptying, and small intestinal propulsion, compared with model group (P<0.05 or P<0.01).Single or two substance groups showed quicker gastric emptying and intestinal propulsive, compared with Simo decoction group (P<0.01), but the difference was not significant compared with the model group（P>0.05）.Conclusion: Arecoline, linderane, hesperidin, costunolide are effective substance of Simo decoction, which can improve gastrointestinal motility function of mice with various degrees of chronic stress.