Abstract: In order to study the safety of transferred human lysozyme cow milk, human lysozyme cow milk gene was used as study subject, and transgenic cow milk was used as control.The differences of milk composition between transgenic and non-transgenic cows were compared, and the molecular structure of the recombinant human lysozyme were analyzed. The results showed that the recombinant human lysozyme was highly expressed in the transgenic cows, and there were 147 different proteins between two groups including antibacterial and bacteriostatic proteins. The fingerprint of the purified recombinant human lysozyme peptide was consistent with natural human lysozyme. The molecular weight of recombinant human lysozyme was 14 691.859 u, and the molecular weight of the two enzymes was similar, and they had the same N-terminal sequence and were all KVFERCELARTLKRL. They all had four types of secondary structures, and the percentages of α-helix, β-corner, β-fold and random coil are 44.62%, 14.62%, 8.46% and 32.30%, respectively. It indicated that genetically modified factors did not cause great changes in the main components of transgenic milk, and the recombinant human lysozyme was basically consistent with natural human lysozyme, which preliminarily proved that milk of transgenic cloned cows expressing human lysozyme was safe in physicochemical property.