Abstract: The emulsifying activity and emulsion stability of ovalbumin were improved by enzymatic modification with Alcalase.On the basis of single factor experiments, and the emulsifying activity as response value, enzymatic hydrolysis duration, p H value and enzymatic hydrolysis temperature were chosen as impact factors. The Box-Behnken center-united experimental design principle was used to design the experiments and the response surface analysis was adopted. The optimal enzymatic modification conditions by the response surface analysis were showed as follows: enzymatic hydrolysis duration 195 min, p H value 9.0, enzymatic hydrolysis temperature 38 ℃, substrate concentration 1.0% and Alcalase usage 30000 U/g. Under the optimal conditions, the emulsifying activity of ovalbumin was 0.967 ± 0.031 increasing with 89.61%, indicating that the effect of improving the emulsification of ovalbumin with alkaline protease modification was ideal.