The disclosure provides a conjugated compound having phenoxathiinl, method for preparing the same and OLED. The conjugated compound has one of the following formulas: Different kinds of electron-rich conjugated aromatic units are reacted with intermediate having phenoxathiinl by Suzuki coupling, Buchwald-Hartwig coupling, or Cu-catalyzed amination of halogenated aromatic hydrocarbons for forming the conjugated compound having phenoxathiin. The prepared novel compound is fluorescent, so that it can be used as the material of light emitting layer of OLED devices.