Chitosan is a kind of natural polymer commonly applied for nanomaterials, which is affluent in nature with favorable biodegradability and biocompatibility and free of toxicity or odor. In clinic it can be used as a drug carrier for the treatment of cancer, and also it is a kind of new pharmaceutical excipient. To prepare chitosan nanomaterial, various method are used, such as ionic crosslinking, covalent crosslinking, precipitation, free radical polymerization, reverse micelle, spray drying, and self-assembly. Furthermore, plenty of anti-tumor drugs, including adriamycin, epirubicin, taxol, 5-fluorouracil, norcantharidin, folic acid, and so on, are also attempted to load on these chitosan nano-carriers. In addition, the mechanism for those nano-carriers carrying anti-tumor drugs acting on tumor cell were explored, and the formulation mainly include electric charge adhesion effect, suppressing the proliferation of tumor cells, adjusting or enhancing immune ability of the body and inducing apoptosis. This paper compared the characteristics of different preparation methods on chitosan as a nano drug carrier, summarized the types of packaged drugs, analyzed the mechanism of the chitosan as nano drug carriers. It can provide valuable reference for researchers' further work.