The invention provides a preparation method of an antifreezing agent, wherein the preparation method comprises the following steps: A, mixing and uniformly stirring glycerinum,
salicylic acid, tea
polyphenol and glacial
acetic acid, adding
acetic acid into the mixture, choosing
liquid paraffin, adding the paraffin into the mixture, stirring uniformly and standing; B, putting bamboo leaves, ochre,
elsholtzia, pine needles into a closed container, adding an
ethanol solution with the
mass percent of 75%, infiltrating and
steeping the
active components for 12 hours, putting the
active components into a percolator, adding the
ethanol solution with the
mass percent of 75%, soaking, starting to collect a percolate, heating the collected 75% ethyl
alcohol percolate, and recovering ethyl
alcohol so as to obtaining an extract; adding the extract into the
vegetable oil, dissolving the extract into the
vegetable oil, heating the
vegetable oil dissolved with drugs to 40-50 DEG C, and sterilizing for use; C, fully mixing the mixture obtained in the step A and the mixture obtained in the step B, and detecting the
ion content, wherein the contents of Cu, Fe, Mn, Zn and B are larger than or equal to 100 g / L. The preparation method is simple in coordination, convenient to use and good in antifreezing effect, and greatly reduces the loss caused by the
freeze injury of a tree.