The transgenic expression vector was constructed by using 9.5kb α-lactalbumin genomic fragment cloned from human cosmid library. Eight transgenic mice （4♂，4♀）were detected by PCR and Southern blot analysis from 68 F₀ mice produced through microinjection. The copy number ranges from 1 to 8, and the integration rate is 11.7%. Human α-lactalbumin have been detected in milk samples of the four founder female transgenic mice by SDS-PAGE gel electrophoresis and Western blotting, and the concentrations of the human α-lactalbumin are quantified to be 0.62g/L, 0.48g/L, 0.56g/L, 3.21g/L respectively by radioimmunoassay (RIA) method. Meanwhile, one offspring of the No.50 male transgenic mice has also expressed the human α-lactalbumin, and the concentration is 1.03 g/L in the milk. The transgenic construct herewith has the characterization of a high-level expression and stable inheritance. A foundation has been provided for improving the quality of cow milk thorough transgenesis of human α-lactalbumin.