The invention discloses a lignum naucleae leaf extract which is characterized in that the extract is obtained by using one of the following methods: (1) the lignum naucleae leaf extract is obtained by water extraction and impurity removal of traditional Chinese medicine lignum naucleae leaves (2) the lignum naucleae leaf extract is obtained by alcohol extraction and impurity removal of the traditional Chinese medicine lignum naucleae leaves (3) the lignum naucleae leaf extract is obtained by lipophilic organic solvent extraction and impurity removal of the traditional Chinese medicine lignum naucleae leaves, and the lipophilic organic solvent includes but not limited by n-butyl alcohol or ethyl acetate. The invention further discloses a preparation method of the lignum naucleae leaf extract, a preparation and a new purpose. The lignum naucleae leaf extract of the invention has exact effects of clearing heat and removing toxin. The extraction process of the invention is simple and reasonable, which can obtain the effective parts. The invention opens up a precedent of obtaining the lignum naucleae leaf extract from the lignum naucleae leaves to be used for the drugs for clearing heat and removing toxin, which can not only ease the shortage of raw materials, but is also conductive to the sustainable and rational development, utilization and protection of lignum naucleae resources.
