The invention relates to a medicament for treating allergic purpura, which is prepared from the following raw materials in portion by weight: 25-35 portions of astragalus root, 10-14 portions of radixscrophulariae, 18-22 portions of rehmanniae praeparatum, 18-22 portions of forsythia, 18-22 portions of rehmanniae vaporata, 9-11 portions of angelica, 18-22 portions of red paeonia, 7-9 portions ofcortex moutan, 18-22 portions of lithospermum, 14-16 portions of double blossom, 18-22 portions of agrimony, 5-7 portions of liquorice, 2-4 portions of safflower, 14-16 portions of salvia miltiorrhiza, 9-11 portions of sanguisorba, 9-11 portions of cattail pollen, 2-4 portions of rush, 9-11 portions of divaricate saposhnikovia root, 14-16 portions of rhizoma belamcandae, 14-16 portions of couchgrass root, 9-11 portions of medlar, 9-11 portions of indigowoad root and 9-11 portions of atractylodes macrocephala. The invention has the advantages of good curative effect, quick response, no toxic and side effects, low cost, convenient taking, treatment of both principal and secondary aspect of disease and no relapse, and can ensure that patients obtain good clinical effect after taking for 3-5 courses.