Po lymer nano par ticles as drug car rier sy st ems is a new kind o f drug deliver y sy stem. It is easy to get to site- specific throug h bio film bar rier fo r the nanoparticles. Po lymer nanopart icles hav e new characterist ics fo r multifo rmity of polymeric mater ial, so po lymer nano par ticles em ployed as drug carr iers hav e att racted attention. In this r ev iew , the tw o prepa rativ e methods for dispersio n of the pr eformed po lymer s and polymerization o f mo nomers are ex pounded, t he measur ing metho d of particles d-i ameter , modality, moleculer w eight, Zeta po tent ial and thermic perfo rmance are investig ated, and the applicatio ns are discussed. At last are the sug g estions o n development t rend fo r polymer nanoparticles as drug car rier