Using methionine and anhydrous ethanol as raw material, p-toluene sulfonic acid as catalyst, and benzene as a carrying water agent, methionine ester was first synthesized. Then, selenium-chelated methionine was prepared through the reaction of methionine ester with sodium selenite by a certain proportion, settling and crystallizing at lower temperature. The ξ potential of the resultant was determined by micro-electrophoresis, through which the isoelectric point was calculated. Based on the principle of isoelectric point, it was separated and purified. The spectral properties of the resultant were analyzed by infrared spectrum, utraviolet spectrum, X ray diffraction analysis and 1H-NMR, from which we got the information of the resultant structure that has a hexagon composing of sulfur atom of methionine, nitrogen of amine and central selenium ion of four-valence.