In this study, extract of elaeagnus angistofolia seed was obtained by supercritical carbon dioxide solvent method and measured the amount of quercetin by using HPLC equipped with UV detector. Experimental results were analyzed by using "Design Expert 7.0 (demo)" program. Increasing temperature and pressure at about extraction conditions caused a significant increase of quercetin amount. Particle size and extraction period parameters was studied parametrically at the start of this study and identified these parameters according to maximize amount of quercetin. After parametric experiments, the small particle size 0.5 mm and experiment period 120 min were found suitable for this study. After identification of these parameters, experimental design conditions identified by response surface design method were used to optimize pressure and temperature, we optimized temperature and pressure parameters as 65 degrees C and 311 bar to maximize quercetin amount. Maximum oil amount was measured 48.68 mg/g sample. After checking experiments of optimum conditions provided by design method, quercetin amount was found experimentally 9.44 mu g quercetin /100 g sample, it was considerably approximate value and favourably to model for estimated 9.49 mu g quercetin /100 g sample by Design Expert 7.0 (demo) program.