Abstract: To make use of oil-tea cake efficiently, ultrasonic-assisted methodology was used to extractplant protein from oil- tea cake with composite solvent. Effects of extracting time, extracting temperature, reaction pH, and ultrasonic power on protein extraction was studied by using response surface methodology.Results indicated that the above influence factor was significant ( p < 0.01) . Based on experiential mathematical model, the optimum extraction conditions were obtained: extracting time was 68min, extracting temperature was 48℃, reaction pH was 10, and ultrasonic power was 350W.The actual oil-tea-cake protein extraction ratio was 71.97%, with err of 0.6% by contrast to predicted value of 72.4%, illustrating experiential mathematical model accurate and reliable.