NOVELTY - Preparation of ligustrazine involves adding 3-hydroxy-2-butanone and ammonium acetate into a reaction container, uniformly mixing, adding ethanol to the mixture and then heating at 79-89 degrees C, adding an aromatization catalyst and glacial acetic acid to the mixture and then filtering to obtain a filtered liquid (A), reacting the liquid (A) to obtain a solution (B), adding water to the solution and then extracting to obtain a solution (C), carrying out decompression process to obtain a solution (D), adding water to the solution (D) and then crystallizing, and filtering.    USE - The method is useful for preparation of ligustrazine (claimed).    ADVANTAGE - The method enables simple, convenient, energy-saving, environmentally-friendly and economical preparation of ligustrazine with high yield of 87%, in a short period of time.    DETAILED DESCRIPTION - Preparation of ligustrazine involves adding 19-21 pts. wt. 3-hydroxy-2-butanone and 19-21 pts. wt. ammonium acetate into a reaction container, uniformly mixing, adding anhydrous ethyl alcohol to the mixture, introducing nitrogen to the container, heating the mixture using a water bath at 79-89 degrees C and then stirring the for 5-8 hours, reducing the temperature to room temperature, where anhydrous ethyl alcohol and 3-hydroxy-2-butanone are used in a weight ratio of 2.8-3.2:1 (ml:g), adding an aromatization catalyst and glacial acetic acid to the mixture and then stirring for 1-2 hours, filtering the mixture to obtain a filtered liquid (A), wherein the aromatization catalyst and ammonium acetate are used in a weight ratio of 35.5-38.5:38-42, the aromatization catalyst is potassium bromate and sodium sulfite in a molar ratio of 0.8-1.2:0.9-1.3, and glacial acetic acid and potassium bromate are used in a weight ratio of 2.5-3.5:1 (ml/g), reacting the filtered liquid (A) for 28-32 minutes to obtain a solution (B), stirring the solution (B) at 30-40 degrees C, adding water to the stirred solution and then extracting using an extracting agent to obtain a solution (C), carrying out decompression and distillation process for 25-35 minutes to obtain a solution (D), adding water to the solution (D), reducing the temperature and then crystallizing to obtain a mixed material (E), where the solution (D) and water are used in a volume ratio of 1:1-2:57, and filtering.