With pepper residues as raw materials,extracting the protein through simple alkali method and ultrasonic waves alkali method were researched.The single-factor experiments showed that ultrasonic waves alkali method was much better than simple alkali method by increasing the protein extraction rate and largely reducing the extracting time.On the basis of orthogonal experimental design,it was concluded that the maximum protein extracted from alkali solution was 86.41% and 60.09% from the sediments after acidification and lyophilization.The best conditions were acquired by the material-liquid ratio 1∶25(m∶V), NaOH 0.3 mol/L, ultrasonic for 120 min with the temperature of 50 ℃ and the ideal isoelectric point tested at pH 3.6.