This experiment was designed to observe the changes in morphology and distribution density of argyrophilic cells in digestive tract of obese rats (Rattus norvegicus) after 8-week exercise by Grimelius silver staining. Rats in exercise group did an 8-week aerobic exercise on the treadmill. SPSS 25.0 and Duncan’s multiple range test were applied to make a statistical analysis of the argyrophilic cells in digestive tract of obese rats from the exercise group and the control group. An independent sample T was applied to test the distribution density of the argyrophilic cells in the same part of the digestive tract of the two groups. The results showed that argyrophilic cells distributed in all parts of digestive tract of rats (Fig. 1), mainly in the form of round, oval, cone and fusiform (Table 4). The highest distribution density of argyrophilic cells in gastrointestinal tract of the two groups was in body of stomach (Table 3). The density of argirophilic cells in the body of stomach in the control group was 112.30 ± 13.42, while that in the exercise group was 98.15 ± 12.53. The distribution density of argyrophilic cells in digestive tract of the control group reached its lowest point in oesophagus and cardia, while in the exercise group that occurred in oesophagus, cardia, jejunum, ileum and rectum. Compared with the control group, distribution density in esophagus and rectum in exercise group was not significantly different (P > 0.05), while there was significant difference in the other parts. The distribution densities of argyrophilic cells in cardia, body of stomach, cecum and colon in the exercise group were significantly lower than in the control group (P < 0.01). The distribution densities of argyrophilic cells in the esophagus and rectum in the exercise group were significantly higher than in the control group (P < 0.01). The distribution densities of argyrophilic cells in the duodenum and ileum in the exercise group were significantly higher than in the control group (P < 0.05). There was no difference in the distribution density of argyrophilic cells in the esophagus and rectum between the two groups (P > 0.05). The changes in the distribution density of argyrophilic cells in the two groups are related to different physiological states and the functions of various parts of digestive tract.