Abstract: To improve the emulsification of zein, this research applied the method of Alcalase hydrolyzation. The hydrolysis condition was optimized on the basis of substrate concentration, reaction temperature, alcalase concentration, pH, reaction time experiments. After the optimal reaction conditions of improving the emulsification of zein were concluded as follows:substrate concentration 2%, reaction temperature 45℃, enzyme amount2200U/g, pH8, reaction time 80 min. Under the optimal condition, the EA of zein was 0.558. The emulsification improved 5.26 times compared with non-hydrolyzed zein.