Objective To study the mechanisms of pathogenicity of %Staphylococcus aureus%(SA). Methods Experimental strains of %S.aureus% were SA1800 and SAm0109. After inoculating with the bacteria, the clinical symptoms and pathogenic changes of experimental mice were examined. Results Obvious invasion of the bacteria was found. The LD 50 of SA1800 to experimental mice was 10 -4.1/0.2 ml, and the LD 50 of SAm0109 to experimental mice was 10 -5.1/0.2 ml. Conclusion It was a good animal model for studying the pathological mechanisms of %S.aureus% and the development of its vaccine.;