The invention relates to an active substance extracted from veronica linariifolia for prostatitis and prostatic hyperplasia treatment, which is effectively used for solving the medicine preparation problem of the treatment of prostatitis and prostatic hyperplasia. The technical proposal of the solution is that the medicinal material veronica linariifolia is fetched, cut up, and arranged in a flask; after immersed with ethanol, reflux extraction and filtration are implemented, and the dregs is added with ethanol to go through reflux extraction and filtration for twice; then the filtrate is merged for three times and decompressed and the ethanol is recycled, extract is derived, proper quantities of water is added to the extract to dissolve thereof, and petroleum benzin is used for extracting for three times; an extraction water layer is added to a polyamide column after concentration and then eluted by distilled water until the eluent is colorless, then 95 percent of ethanol is used foreluting; the eluent is collected until no flavone ingredients are contained; the ethanol is recycled and evaporated on a water bath, thus veronica linariifolia total flavonoids active substance is derived; the substance is effectively used in the preparation of the treatment medicines of prostatitis and prostatic hyperplasia and opens up a novel filed of veronica linariifolia preparation medicines, which is a great innovation in Chinese medicine and is beneficial to human beings.