This invention relates to salts of sulfodehydroabietic acid with bismuth or zinc, a kind of new salt useful in treating digestive canal ulcer, acute & chronic gastritis, and erosive gastritis etc., as well as its preparation and use. Said salts can be represented by formula (1), wherein R is Bi(OH)⁺⁺ or Zn⁺⁺, 2Bio⁺, 1/2ZnH, n=0-10. The preparation method comprises following steps: (a) sequentially treating the industrial abietic acid calcium salt with acid, base and extracting with organic solvent to give abietic acid with less isomer; (b) reacting said abietic acid with Pd/C to provide dehydroabietic acid, then converting it to pure sulphonic product, namely sulfodehydroabietic acid, via sulphonation and recrystallization; (c) by use of neutralization or salt displacement reaction to convert the sulphonic product of zinc or bismuth salts of sulfodehydroabietic acid. The resultant salts can used to prepare medicine for treating digestive canal ulcer and gastritis. ##STR1##