The extraction of iron(II) from sulfuric acid media by primary amine N1923 was investigated. The pocket effect was proposed for the first time by using IR spectra and TEM. When the concentration of extractant reached to 0.05 mol/L, primary amine N1923 formed the spherical reversed micelle, which could improve the distribution coefficient of extraction greatly, and the pocket effect emerged. The whole action of extraction contained the two kinds of mechanism, ionic complex extraction and micelle solubilization, the extraction equation can be showed as follows: D = K(1)c(N1923) + K(2)c(m)(N1923).