Abstract: Extracted aristolochic con-acid by dehydrate alcohol as the solvent from 150 g manchurian dutchmanspipe stem powder,get crude extract after rotary evaporation and vacuum dehydration，and dissolved extractum with NaHCO₃ saturated solution，adjusted the pH to 3 after delamination.Used silica gel G chromatographic colum to laminar analysis. The eluent was made up of chloroform∶acetidin∶methylbenzol(2∶1∶1).Then get flav-crystal 0.389g after recrystallization, identified and assayed the content with R-HPLC. the result showed that the flav-crystal was aristolochic acid A monomer, and the content reached 99.2%. The methold of extraction could get high purity aristolochic acid A,and it was a high performance way.

Key words: manchurian dutchmanspipe stem; aristolochic acid A; extraction; assaying