Nanotechnology provides researchers with new tools for cancer treatment. Biodegradable polymeric nanoparticles, as an advanced drug delivery system, have promising applications in cancer treatment. Poly(- caprolactone)/poly(ethylene glycol) (PCL/PEG) copolymers are biodegradable and amphiphilic, and show potential application in drug delivery. In recent years, PCL/PEG copolymeric nanoparticles, as a potential nanoplatform for anticancer agent delivery, received increasing attention. This paper reviews PCL/PEG copolymer nanoparticles for anticancer agent delivery, including overcoming water insolubility of hydrophobic drug, targeting chemotherapeutic drug to tumor, and delivering genes, vaccines, and diagnostic agents.