Blanching conditions for immatured soybeans were optimized by analyzing the effects of various time/temperature blanch treatment on the activities of peroxidase and lipoxygenase, the stability of vitamin C and color, and moisture content in immatured soybeans for the purpose of minimizing quality deterioration during frozen storage. Blanching at 96$^{circ}C$ for 70 sec led to maximum inactivation of lipoxygenase in the immatured soybeans, while my blanching conditions tested in this study were not enough to inactivate peroxidase. Blanching at 82$^{circ}C$ for 60 sec resulted in the highest amount of vitamin C remaining in the immatured soybeans after blanching. Hunter -a/b ratios of immatured soybeans blanched at 82$^{circ}C$ for 60 sec and hue values (ΔE) of the immatured soybeans blanched at 76$^{circ}C$ for 60 sec showed the closest values to those of fresh products. The changes in moisture content of immatures soybeans was not so significant after blanching. In conclusion, it was suggested that immatured soybeans be blanched at 96$^{circ}C$ for 70 sec to minimize lipoxygenase activity and resulting quality deterioration, while blanching at 82$^{circ}C$ for 60 sec was recommended to stabilize vitamin C and color.