The objective of this study was to evaluate the nutritional quality of reconstituted milk by determining concentrations of several important proteins. Difference in protein between raw milk and reconstituted milk was determined with spectrophotometer, HPLC, fluorometry, ELISA, photon correlation spectroscopy. Total undenatured whey protein, β-lactoglobulin, α-lactalbumin, chemically available lysine, insulin-like growth factor-Ⅰ (IGF-Ⅰ), epidermal growth factor (EGF), immunoglobulin G (IgG) contents and casein micelle size were analyzed for both raw milk and reconstituted milk. Results showed that reconstituted milk had a significant decrease (P<0.01) in total undenatured whey protein, β-lactoglobulin, α-lactalbumin, chemically available lysine, IGF-Ⅰ, EGF and IgG. The decrease of casein micelle particle size confirmed that most of the whey protein denatured and associated with the casein micelle occurred in the processing of milk powder manufacture. It is concluded that reconstituted milk has a lower nutritional value than that of raw milk.