Abstract: OBJECTIVE To compare the protective effect of ultramicro-powder and powder of Codonopsis Radix on gastric mucosa of gastric ulcer in rats. METHODS The model of gastric ulcer were set up by acetic acid, after treated by the two kinds of powder for 10 d, to measure the gastric ulcer area and count out the inhibitory rate. The levels of gastrin and 6-keto-PGF1α were measured by radioimmunity, EGF were measured by ELISA method. RESULTS Ulcer index of the ultramicro-powder group and powder group were lower than that of model group, and it in the ultramicro-powder group was lower than the powder group. The levels of gastrin in ultramicro-powder group were obviously lower than that in powder group, while the levels of 6-keto-PGF1α and EGF in ultramicro-powder group were obviously higher than that in powder group. CONCLUSION The therapeutic effect on gastric mucosa damage of ultramicro-powder of Codonopsis Radix is superior to the powder. The efficacy of Codonopsis Radix can be improved by superfine comminution.