Abstract: A nanocomposite, a preparation method thereof and a method for treating cancer using the same are provided. The preparation method includes: mixing a first solution including an amphiphilic chitosan and a second solution including anti-cancer components, wherein the anti-cancer components includes gemcitabine, curcumin, the derivatives and combinations thereof; forming a nanoparticle encapsulating the anti-cancer component by a self-assembling process of the amphiphilic chitosan, and binding the nanoparticle with a targeting molecule having specificity to a cancer so as to obtain a nanocomposite. When dissolving the nanocomposite of the present invention after drying into water phase, the nanocomposite still has the same morphology and characteristic before it is dried, so it is convenient for storage and delivery. Additionally, the preferable ratio of gemcitabine and demethoxycurcumin will bring a synergistic effect on cancer therapy.