The invention discloses an N-carboxyanhydride monomer based on 2-aminohexadecanoic acid and polyamino acid as well as a preparation method thereof. The method comprises the following steps: firstly, preparing 2-aminohexadecanoic acid-N-carboxyanhydride monomer, and preparing by the monomer to obtain polymers, wherein the distribution of the molecular weights of the obtained polymers is narrower, the polymers have excellent biocompatibility and can be used for controlling drug delivery systems; nano-medicines of the prepared cRGD-modified polymer micelles and polymer vesicles support in-vivo stable long-circulation, the nano-medicines are highly enriched on tumor cells and effectively enter cells, and can be released in the cells, so that cancer cells can be effectively and specifically killed, and the growth of subcutaneous tumors and tumors in situ are effectively inhibited so as not to obviously cause toxic and side effects.