Abstract: Novel biodegradable amphiphilic copolymer nanoparticles based on dextran and poly (lactide) have been prepared.To estimate the feasibility as drug carriers,an anti-tumor model drug doxorubicin (DOX) was successfully incorporated into polymeric nanoparticles by double emulsion (DE) and nanoprecipitation (NP) methods.The DOX-loaded nanoparticles were confirmed by dynamic light scattering (DLS),transmission electron microscopy (TEM) and ultraviolet (UV) absorption spectrometry.The DOX-loaded nanoparticle size,size distribution and encapsulation efficiency (EE) were influenced by the feed weight ratio of the copolymer to DOX.In addition,in vitro release experiments exhibited the release behavior was affected by pH of release media.The DOX-loaded nanoparticles release slower in pH 7.4 than in pH 5.0 buffer.The dextran-co-PLA polymeric nanoparticles can be useful as drug carriers for anti-tumor drug delivery.