Abstract: Carboxymethyl chitosan grafting ricinolic acid copolymer (CMC-g-RA) was prepared by the acylation reaction of ricinolic acid anhydride (RAN) and carboxymethyl chitosan (CMC).The influence of factors such as molecular mass,mole ratio of anhydride/amino,reaction temperature and solvent on substituting degree of CMC-g-RA was investigated.Rot and CMC-g-RA,as a botanical pesticide and a carrier,were used to prepare a novel nanoparticle aqueous dispersion by dissolving Rot in the micelle formed from macromolecular chain self-assembly.Physics properties of the nanoparticle aqueous dispersion,such as particle size and dispersion,surface charge and loading efficiency as well as morphology structure,were characterized.Influence of solution concentration for CMC-g-RA and Rot on above properties was discussed.It is showed that the nanoparticles prepared from CMC-g-RA and Rot have smooth and close rotundity shape,particle sizes of 200-500 nm,narrow particle size distribution and negative surface charge.Zeta potential value of the nanoparticles are from -40 to -70 mV and increased with an increase in the concentrations of Rot and CMC-g-RA.The loading efficiency for nanoparticles are of a range of 20%-68%.In conclusion physics properties were controlled by matching concentration of CMC-g-RA and Rot,and loading efficiency could be regulated effectively,which the balance between fast effect and controlled release of the pesticide formulation can be tailored consequently.