We studied 128 patients with active peptic ulcer diagnosed by gastro-endoscopy four weeks after treatment with Xi Lei powder, PGE2 levels in both serum and gastro-duodenal mucosa were significantly higher than that before the treatment, the difference was significant (P < 0.01). The rate of negative conversion of Helicobacter pylori (HP) showed in 63.3% of cases. The distributed density of HP significantly reduced, the difference was significant (P < 0.01). These results indicated that Xi Lei powder could heal ulcer probably owing to the increasing of the PGE2 level in gastroduodenal mucosa, it inhibited the growth and reproduction of HP, and eliminated the HP, but did not inhibit the secretion of gastric acid and release the gastrin.