OBJECTIVE： To optimize extraction technology of protein from Cryptotympana pustulata and investigate its in vitro antioxidant activity， so as to provide reference for further research of protein from C. pustulata. METHODS： Using extraction amount of protein as response value， based on single factor test， Box-Behnken response surface methodology was used to optimize the ratio of liquid to material， ultraonic time and extraction times. Validation test was conducted. Using Vitamin C （VC） as positive control， in vitro antioxidant activity of protein from C. pustulata was evaluated by using scavenging rate of 1，1-diphenyl-2-picrylhydrazyl （DPPH） and 2，2′ -azino-bis（3-ethyl benzothiazoline-6-sulfonic acid） （ABTS） free radical as index. RESULTS： The optimal extraction condition of protein from C. pustulata was as follows as the ratio of liquid to material 28 ∶ 1 （mL/g）， ultrasonic time of 65 min， extracting for twice. In validation test， average extraction amount of protein from C. pustulata was 65.45 mg/g（RSD＝1.68％，n＝3）， relative error of which to predicted value was 5.48％. The protein from C. pustulata showed strong scavenging effect on ABTS and DPPH free radicals. When the concentration of protein from C. slough was 0.2 mg/mL， and the scavenging rate of it to ABTS free radicals was 97％， the effect of which was similar to VC. The protein from C. pustulata showed weak scavenging ability to DPPH free radical， IC50 was 0.96 mg/mL， the effect of which was not as good as VC. CONCLUSIONS： The extraction technology of protein from C. pustulata optimized by Box-Behnken response surface methodology shows high accuracy and good reliability. The protein from C. pustulata shows certain antioxidant activity in vitro.