Effects of pretreatment and extraction conditions on total polyphenol yield from licorice root were investigated using statistical method. For pretreatment, heat treatment at 121°C for 10 min was applied. Licorice root content in solvent (10, 20, and 30%) ethanol concentration (20, 40, and 60%) and reaction time (1, 2, and 3 h) were used as variables for extraction conditions. Two experiments, with heat treated and no treated licorice, were prepared with same experimental design. Box behnken design was employed and produced a total of 15 trials. Total polyphenol yield from licorice root was not affected by heat treatment. Among variables, licorice content in solvent showed most significant effect regardless of other variables (p<0.05). Finally, optimum conditions for the extraction of total polyphenol from licorice root was detected as following: 10% of licorice in solvent, 52% ethanol as solvent, 2 h of reaction time and non-heat treatment and the extraction yield from optimized condition was 17.6 mg/g licorice root.