Abstract: Nano-sized spherical polyelectrolyte brush (SPB) refers to a kind of macromolecular self-assembled structure that polyelectrolyte chains densely attach on spherical nanoparticles by one end. This unique structure can regulate the surface properties of nanoparticles, which makes SPB become suitable candidate in preparation for nano-metal catalysts, controlled drug delivery and protein separation. In recent years, the preparation methods of SPB are developing, and the application range is continuously expanded. SPB has become one of the hotpots in the area of polymer science. In this paper, the latest progress on SPB synthesis and applications are systematically reviewed, and some possible directions for further research are forecasted.