Abstract: The protein proteolysis-targeting chimeras (PROTAC) are a kind of bifunctional compound that can recruit target proteins and degrade the enzyme of target proteins. The mechanism of PROTAC is using the ubiquitin-proteasome pathway to degrade target protein specifically. Because of its potential to target non-proprietary proteins and to play roles in drug resistance, PROTAC has attracted wide attention. This review summarizes the application of small molecule PROTAC in previous studies of different targets, such as nuclear proteins, membrane proteins and cytoplasmic proteins.