With a proposed new ruminant protein system, the study on amino acid nutrition entered into a new phase. The metabolism of proteins, limiting amino acids and peptides, amino acids with a reasonable diet, the improvement of feed protein digestibility and nitrogen utilization have become new hot topics in the field of ruminant nutrition. This paper reviewed the amino acid restrictive sequence, study methods of limiting amino acids, ideal amino acid research pattern, metabolic mechanism of methionine and lysine, and the influence factors of limiting amino acid metabolism of rumen microorganisms i...