Abstract: How to increase the reco very rate of amino acids in feedstuff analy sis was discussed in this paper.The exper imental results showed that,the values of sulfur amino acids(cystine and methio nine)were incr eased by oxidizing samples before hydrolysis.The recovery rate reached 91.3%and 91.7%,respectively.However,this procedure caused loss of tyrosine and other amino acids.After purifying halogen and discontinue oxidation,the above shortcomings were over came. So a high recovery rate,simple and reliable technicue procedure of pretreatment in feedstuff amino acid analysis was developed.