Abstract: A new process that defatted peanut was pretreated by Viscozyme L before extraction of the protein with a method of alkali solution-acid precipitate was put forward, and the effects of the enzyme pretreatment conditions on the extraction rate of peanut protein was researched by central composite design experiments and Response Surface Methodology (RSM). Results showed that the extraction rate of peanut protein was 79.38% under the optimum pretreatment conditions: 15%(m/V) content of defatted peanut flour suspension, temperature of 45℃, pH 4.3, 1.26% of Viscozyme L and reaction time of 134 min. Yet the extraction rate of peanut protein without pretreatment was only 58.35%. The results indicate that the enzyme pretreatment is helpful for the extraction of peanut protein.