The effect of different soaking time on polyphenol, flavone, DPPH scavenging activity, ABTS+·scavenging activity and total antioxidant activity of mung beans soaking solution was studied, and the correlation between polyphenol, flavone and antioxidant activity was also analyzed. The results showed that the contents of polyphenol and flavone increased rapidly and DPPH scavenging activity, ABTS+·scavenging activity increased significantly along with the increase of soaking time within 4~12 h. The increasing rate slowed down gradually till no obvious changes after 12 h. The total antioxidant activity increased rapidly with the increase of soaking time within 4~8 h, then maintaining slow growth and the activity reached maximum when soaked for 24 h. The contents of polyphenol and flavone were significantly correlated to antioxidant activity (P<0.01).