Abstract: In this paper, a novel two-stage enrichment process was developed for mass-producing ACE-inhibitory peptides by using casein peptide phosphate production by- products ( CPPBP) .After pre- concentrating active peptides on the basis of analyzing separation properties of CPPBP, the high efficient components were located by hippuric acid method and HPLC method.And then a three factor and three levels orthogonal experiment, taking yield of high efficient components as index, was designed to optimize the process conditions of concentrating ACE- inhibitory peptides.In first stage, saturated CPPBP solution was used as material and precipitation conditions were set as pH2 and-16℃ for 1h.The pre- concentration was named as Pcrude.In second stage, the final product was precipitated from saturated Pcrudeunder pH4, Ethanol concentration 70% and- 20℃ for 1h.The yield of enrichment process was 19.11% with an inhibition of 46.29% to ACE.