To investigate the food preservative effects of leaf mustard Dolsan(Brassica juncea), the pretreated extract of leaf mustard Dolsan were added to Kimchi and the results are as following. pH of Kimchi added leaf mustard Dolsan extracts were lower than that of control at initial stage, but after 6 days of fermentation, pH was higher in order of Kimchi added the pretreated extract of leaf mustard Dolsan (hydrolyzed at 3$0^{circ}C$ for 24 hours, PEM), the unpretreated extract of leaf mustard Dolsan(UEM) and control. The total number of bacteria and lactic acid bacteria increased rapidly at the initial stage of fermentation and reached plateau at 2 days of fermentation. The number of bacteria and lactic acid bacteria of Kimchi added leaf mustard Dolsan extracts were lower than that of control ,a and antimicrobial activity of PEM in Kimchi was higher than that of UEM. After 2 days fermentation, sensery value of Kimchi added PEM was more excellent than that of control.