The isolate Staphyhcoccus sp. YZ14 was selected for it's ability to produce lysostaphin, and this bacterium identified as Staphylococcus aureus YZ14. according to morphological, physiological and biochemical characteristics, which confirmed by API Staph system. In order to determine whether the genes responsible for lysostaphin production are located on the plasmid or chromosome, many attempts were made to cure Staphylococcus aureus YZ14 plasmid by using SDS, and the result indicated that no cured strains (that fail to produce lysostaphin enzyme) \\ere obtained. This indicates that the lysostaphin production trait in Staphylococcus aureus YZ14 may be located on chromosome. The optimum conditions for mutagenesis of Staphylococcus aureus YZ14 were determined in order to use it in isolation of different mutants from this bacterium and the lethal and mutagenic effect of UY light and MNNG were studied on this bacterium. Results indicated that this bacterium was sensitive to lethal and mutagenic effect to both mutagens and the optimum conditions for mutagenesis of this bacterium is treat this bacterium with 30 ug / ml of MNNG in nutrient broth for 20 min. The optimum conditions for mutagenesis of Staphylococcus aureus YZ14 were used to get lysostaphin high level producer mutants from this bacterium. Fifteen colonies were selected and screened for their ability to produce lysostaphin enzyme. Results showed that lysostaphin activity was varied between these colonies and two mutants (M8 and Ml4) showed high lysostaphin activity.