NOVELTY - Preparing 1-acetyl L-carnitine hydrochloride involves taking levocarnitine hydrochloride as staring raw material, acetic anhydride as acylating agent, catalyst, at 70-75 degrees C for 3 hours, cooling to 20-25 degrees C, using ether pulping washing, adding alcohol stir for 2-3 hours to crystallize, obtain a product with a single alcohol or a mix solvent heating rear dissolve and adding active carbon decoloring and re-crystallizing, Where (1) levocarnitine hydrochloride and acetic anhydride whose mol ratio is 1:1-1.5, (2) carnitine hydrochloride with the weight ratio of catalyst is 10:1-1.5, (3) a selected catalyste ptoluenesulfonic acid, trifluoroacetic acid, perchloric acid, (4) pulping washing with ether is selected from diethyl ether, methyl tertiary butyl ether, isopropyl ether, (5) separating out crude product in process of adding alcohol is selected from ethanol, isopropyl alcohol, n-butyl alcohol, (6) recrystallizing is selected from a solvent selected from ethanol, isopropanol, ethanol-isopropanol, isopropanol-water, ethanol-acetone, isopropanolacetone, ethanol-water, (7) re-crystallizing solvent amount of crude product weight of 2-10 times (vol./wt.%), (8) adding activated carbon to 5-15 wt.% of crude acetyl L-carnitine hydrochloride.    USE - For preparing 1-acetyl L-carnitine hydrochloride (claimed).    ADVANTAGE - The method has simple operation, mild condition, it does not need a special reaction device; process is simple, has good product quality, high yield. It will not produce large amount of glacial acetic acid waste liquid and is environment-friendly.    DETAILED DESCRIPTION - Preparing 1-acetyl L-carnitine hydrochloride involves taking levocarnitine hydrochloride as staring raw material, acetic anhydride as acylating agent, lower the catalyst, at 70-75 degrees C for 3 hours, cooling to 20-25 degrees C, using ether pulping washing, adding alcohol, stirring for 2-3 hours to crystallize, obtain a product with a single alcohol or a mix solvent heating rear dissolve and adding active carbon decoloring and re-crystallizing, where (1) levocarnitine hydrochloride and acetic anhydride whose mol ratio is 1:1-1.5, (2) carnitine hydrochloride with the weight ratio of catalyst is 10:1-1.5, (3) a selected catalyste ptoluenesulfonic acid, trifluoroacetic acid, perchloric acid, (4) pulping washing with ether is selected from diethyl ether, methyl tertiary butyl ether, isopropyl ether, (5) separating out crude product in process of adding alcohol is selected from ethanol, isopropyl alcohol, n-butyl alcohol, (6) a recrystallizing is selected from a solvent selected from ethanol, isopropanol, ethanol-isopropanol, isopropanol-water, ethanol-acetone, isopropanolacetone, ethanol-water, (7) re-crystallizing solvent amount of crude product weight of 2-10 times (vol./wt.%), (8) adding activated carbon to 5-15% of crude acetyl L-carnitine hydrochloride.