Breast milk is of great importance to the neonatal animals as a unique source of food. Proteins are the most critical nutrients in milk. Knowledge of this complex protein system has evolved incrementally in recent years with the application of proteomics and associated technologies. In this article we review the progress of milk proteomics in the comprehensive identification of milk composition including main whey proteins and milk fat globule proteins, regulation of lactation and characterization of allergens in milk.［Chinese Journal of Animal Nutrition, 2009，21（6）:809-815］