Abstract: This study evaluated the sizes of reverse micelles before and after the extraction of peanut protein by AOT/isooctane reverse micelles and investigated the relationship between the size change and extraction rates.The results showed that increasing the concentration of KCl,the particle sizes and forward extraction rates decreased. And increasing the concentration of AOT in the range of 0.04 ~0.09 g/m L,the empty reverse micelles and full reverse micelles increased,forward extraction rates increased,while the backward extraction rates were on the contrary. The p H had no significant influence on empty reverse micelles,but could influence full reverse micelles sizes and extraction rates by electrostatic interaction. The ion species had significant effects on the sizes of reverse micelles and extraction of peanut protein,when the addition amount of buffer solution containing Mg Cl2 was 0.03 m L/m L,the forward extraction rate reached the peak of 98.55%±0.60%. The relationship between reverse micelles sizes and extraction rates could influenced by many factors,and their relation varied under different conditions. The model of the forward extraction process was “water-shell model”.