Lactoperoxidase(LPO)activity is an important index to evaluate the heat treatment intensity during milk processing.In this study,the activity of milk peroxidase in milk was determined by colorimetric method,and the changes of milk peroxidase activity in milk under different thermal sterilization process conditions were discussed.The results showed that under suitable pasteurization conditions(72~77 ℃,15 s),milk peroxidase in milk could retain 1 581.44~3 720.20 U·L-1 enzyme activity,while high-intensity heat treatment results in complete inactivation of lactoperoxidase in milk.