Methionine is a sulfur-containing amino acid. Methionine provides methyl for the synthesis of choline in vivo, and choline is a component of lecithin. Lecithin is an indispensable material for fat transport out of the liver and clearing fat deposition in the liver. Therefore, methionine also has the lipid chemotaxis of choline. In addition, methionine is supplied with sulfur in the chemical book in vivo to synthesize non exogenous amino acid deamination, which has detoxification effect. Therefore, this drug is clinically a lipid chemotactic and liver protecting drug, which is suitable for fatty liver, chronic hepatitis and liver cirrhosis with fat infiltration. Clinically, methionine can also be used as an adjuvant drug for alcohol and sulfonamide poisoning.