This paper mainly studies the relationship between the effect of ultrasound on the enzyme activity of sodium alginate immobilized papain and the effect of ultrasound on the structure of alginate gels. On the basis of single factor experiment,the best ultrasound conditions were obtained through the uniform design test method( 40 kHz,0.45 W/cm2,20 min,70 ℃),the predicted relative enzymatic activity was 342.64%. The impact of ultrasound on the structure of alginate gels was studied.Electron microscope and digi...