The continuous expanding of targets is a distinct character of systematic evolution of ligands by exponential enrichment (SELEX) technique and other random library technologys (such as phage display technology). Over the past 20 years the targets of SELEX have expanded to various metal ions, organic molecules, drugs, proteins and biomacromolecules, pathogenic bacteria, live cells and tissue slide. The SELEX screenings using live cells and tissue slide as targets have been preliminarily applied for studying targeted diagnosis and treatment of cancers. This paper reviews the expansion of the targets of SELEX technique.