The invention discloses a novel method for preparation of a chitosan nano carrier and functionalization thereof, which relates to the chitosan nano carrier. The invention provides a novel method for preparation of the chitosan nano carrier and functionalization thereof. The chitosan is dissolved in acetic acid solution, meanwhile, pH is adjusted to 4.5-5.5 with NaOH solution, STPP (sodium tripolyphosphate) solution is added to the chitosan solution to obtain nanogels, then, crosslinking glutaraldehyde is provided for the chitosan, centrifugation is conducted after ending of reaction, reduction reaction is conducted with excess sodium borohydride, then centrifugation is conducted again, then, the obtained compound is dispersed in hydrochloric acid solution to remove the unreacted sodium borohydride, then dialysis is conducted, in order to wash STPP to obtain nanoparticles; the folic acid is weighed to be dissolved in the phosphate buffer solution, then the solution is added to chitosan nanoparticles water solution, after adding EDCI to the solution, folic acid modified nanoparticles are obtained through reaction; PEG succinimidyl propionate is weighed to be dissolved in the phosphate buffer solution, then is added to the chitosan nanoparticles water solution, after reaction, PEG modified nanoparticles are obtained.