The crystal structure of ethylenediaminetetraacetic acid has been determined by the method of symmetry elements. The crystal is monoclinic, space group C2h6, with parameters a=13.28?,b=5.64?,c=16.14? and β*=83°45′. Each unit cell has four molecules. The interatomic distances are calculated and discussed.From the result of crystal structure, two carboxyls in the ethylenediaminetetraacetic acid form internal molecular hydrogen bonds with the two nitrogen atoms. Therefore, chemical characters of the ethylenediaminetetraacetic acid can only have those of a dibasic acid. The structure formular of molecule should be