To investigate the effects of Baizhu Qiwu granule on gastrointestinal function in colon slow transit constipation mice and its related mechanisms.Methods:A total of 40 ICR mice were constructed colon slow transit constipation mice model by given compound diphenoxylate orally，and 10 cases of mice were given equal amount of normal saline orally as blank group.38 cases of successful constipation models were randomly divided into model group (n＝9)，positive control group (n＝9) and low/high dose test group (n＝10，test groups-L/H).The test groups-L/H were given orally 16.3 g/kg and 65.2 g/kg respectively of Baizhu Qiwu granule raw medicine，and the positive control group was given orally 2 g/kg mosapride citrate tablets.The model group and the blank group were given equal amount of normal saline orally once daily for 14 d continuously，and 1 mL nano carbon suspension was given at the same time when the last administration was given in each group.After intervention，the defecation of mice in each group was observed，and the activities of intestinal enzyme were measured.Immunohistochemistry was used to detect the expression of 5-hydroxytryptamine 4 (5-HT4)，vasoactive intestinal peptide (VIP)，nitric oxide (NO) and P substance (SP) in colon tissue.Results:Compared with the blank group，the time of first time black stool in the model group prolonged，and the number of defecation particles decreased.The total weight of feces decreased (P<0.05).Compared with the model group，the time of first time black stool in the positive control group and the test groups-L/H shortened，and the number of defecation particles increased.The total weight of feces increased (P<0.05).There was significant difference between test group-L and test group-H (P<0.05).Compared with the blank group，the activity of intestinal protease and cellulase of the model group decreased and the activity of xylanase increased (P<0.05).Compared with the model group，the activity of protease and cellulase in the positive control group and the test groups-L/H increased，the activity of xylanase decreased (P<0.05).The difference between test group-L and test group-H was significant (P<0.05).Compared with the blank group，the expression of VIP and NO in the colon tissue of the model group increased and the expression of 5-HT4 and SP decreased (P<0.05).Compared with the model group，the expression of VIP and NO in the colon tissues of the positive control group and the test group-L/H decreased，and the expression of 5-HT4 and SP increased (P<0.05).The difference between test group-L and test group-H in the expression of VIP，NO，5-HT4 and SP proteins was significant (P<0.05).Conclusion:Baizhu Qiwu granule can regulate the activity of intestinal related enzymes in colon slow transit constipation mice and improve the gastrointestinal function，which may be related to the regulation of the expression of 5-HT4，VIP，NO and SP proteins in colon tissue.