To investigate the effects of the traditional Chinese medicine GSXJG (Geshan Xiaoji Granules) on gastric motility, a systematic study was conducted by combining an in vitro gastric smooth muscle activity assay using the drug-containing serum method with in vivo animal experiments. GSXJG-B (drug-containing serum) and KB-B (blank rat serum) were prepared from rats, and longitudinal smooth muscle strips from the gastric antrum and fundus were isolated from healthy rats. A physiological muscle recording system was used to evaluate the effects of GSXJG-B at different concentrations on the contractile tension of isolated gastric smooth muscle. Healthy KM mice were randomly assigned to five groups: a blank control group, a Jianwei Xiaoshi Tablet group, a low-dose GSXJG group (5 g/kg), a medium-dose GSXJG group (10 g/kg), and a high-dose GSXJG group (20 g/kg). After intragastric administration of the corresponding treatments for three consecutive days, the gastric residual rate and small intestinal propulsion rate were measured. Serum levels of VIP (vasoactive intestinal peptide), GAS (gastrin), and MTL (motilin) were subsequently determined using ELISA (enzyme-linked immunosorbent assay). The results demonstrate that, in the in vitro gastric smooth muscle experiments, compared with pre-administration conditions, KB-B significantly enhances the contractile tension of isolated gastric fundus smooth muscle strips in rats at concentrations ranging from 40 to 320 μL, showing a clear dose-dependent positive correlation. Notably, this promotive effect is nearly twice that observed in the blank serum group at the corresponding concentrations. GSXJG-B exhibits an overall inhibitory tendency on gastric antrum smooth muscle strips; However, its promotive effect on contractile activity is greater than that of the corresponding KB-B, and at the highest concentration, GSXJG-B produces a mild excitatory effect on gastric tension. In normal mice, low-dose GSXJG significantly increases the gastric residual rate, while the gastric residual rates in the other GSXJG-treated groups are also higher than that in the blank control group. High-dose GSXJG significantly enhances the small intestinal propulsion rate. Moreover, all three GSXJG doses significantly elevate serum MTL levels, and the low-dose group showes a significant increase in serum VIP levels. In contrast, the Jianwei Xiaoshi Tablet group shows no significant effects on gastric residual rate or small intestinal propulsion rate, but exhibits a trend toward decreased VIP levels and increased GAS levels. Overall, these findings indicate that GSXJG enhances gastric motility by promoting gastric fundus smooth muscle contraction and accelerating small intestinal propulsion, and that these effects are associated with the modulation of gastrointestinal hormone secretion.