Abstract： The effects of modifiers on the extraction of cobalt(II) and iron(II) with tertiary amine were investigated. It was found that additional modifiers, oxygen-containing organic compound(HA3), had the synergism with tertiary amine for cobalt extraction and also changed the property of the iron extraction. The loaded iron(II) can not be stripped by dilute acidic solution. Cobalt(II) and iron(II) could be separated by using scrubbing and stripping. The new technology of separation of cobalt(II) and iron(II) extractive, with tertiary amine from chloride solution was proposed, which avoids the preoxidation of iron(II).