Abstract: The activated folate molecular was conjugated to O-carboxymethyl chitosan(O-CMCS), and the nanoparticles were prepared by ionic cross-linking method using CaCl2 as the cross-linked agent, then the nanoparticles used as the carrier of paclitaxel (PTX) were studied. Results showed that the nanoparticles were spherical and the particle size was about 200 nm. The drug loading content (DLC) and encapsulation efficiency (EE) were both effected by adding PTX. The nanoparticles had a good pH-sensitivity to the drug release which could enhance the PTX enrichment in cancer cells. Meanwhile, the nanoparticles with no toxicity on normal cells, had a good targeting ability to cancer cells as the existence of folate on O-CMCS and also had a good growth inhibition effect on cancer cells.