Abstract: Hemolysates of 41 kinds of animals including human,fetal and monkey's one,were studied by isoelectric focusing on PAG Plate (pH3.5-9.5).Species featuces of Hb band pattern,ability for identification and alternation of Hb band pattern after treatment with P-Chloromercuribenzonate (PCMB) as well as its influence on the species identification of Hb were disscused as well.Approaching to the application of IEF for identifying species gave the following results:Class of animals can be identified hy characteristic distri- bution of the band pattern;Human Hb may be distinguished from that of other animals but monkey's one of which band types somewhat difficultly discriminated because of similar band type,Differences of band patterns are also shown between animals,which may be used for identification.Aftry treatment with PCMB,both human and monkey's Hb are broken down to and β subunit.The different PI value of α subunitin both human and monkey's Hb can be used for identification and much easily to distinguish human Hb from that of the other animals.