NOVELTY - Artemisinin is prepared from waste acid and artemisinic acid by primary molecular distilling, molecular distilling heavy phase, extracting with petroleum ether, discarding insoluble material, extracting with alkaline solution, adding acid solution, adjusting pH, extracting with organic solvent, precipitating, drying with anhydrous sodium sulfate, mixing urea and ethanol, mixing urea solution and concentrated product, rapid filtering, recovering ethanol, washing with distilled water and organic solvent, drying with anhydrous sodium sulfate and crystallizing.    USE - Method for preparing artemisinin from waste acid and artemisinic acid (claimed).    ADVANTAGE - The method is environment-friendly, low cost and suitable for industrial production.    DETAILED DESCRIPTION - Artemisinin is prepared from waste acid and artemisinic acid by:    (A) primary molecular distilling to separate heavy phase from light phase, molecular distilling heavy phase to obtain crude product containing 20-50 wt.% artemisinin, extracting with petroleum ether at 60-90 degrees C and 50 degrees C, and discarding insoluble material;    (B) extracting for 31 times with alkaline solution, adding acid solution, stirring, adjusting to 1-3 pH, extracting with organic solvent, precipitating, drying with anhydrous sodium sulfate, filtering, heating at 50-80 degrees C under greater than or equal to - 0.07 MPa pressure, and concentrating under reduced pressure to obtain concentrated product;    (C) mixing urea and 95 vol.% ethanol, heating at 50-80 degrees C, and dissolving to obtain urea solution; and    (D) mixing urea solution and concentrated product, dissolving, stirring at 20-25 degrees C, cooling at - 20-0 degrees C for 12-48 hours, rapid filtering, recovering ethanol, washing with distilled water and organic solvent at 2:4 volume ratio, drying with anhydrous sodium sulfate, filtering, heating at 50-80 degrees C under greater than or equal to - 0.07 MPa pressure, concentrating, cooling to 20-25?C for 3 hours, filtering, and crystallizing.