As an important drug for the treatment of cancer, cis-diamine dichloroplatinum (CDDP) has poor solubility and antagonistic effect when it is used as a chemotherapy agent alone, leading to the insufficient dose in actual administration. In order to solve the above problems, increase the targeting property of CDDP carrier and prolong the half-life period of CDDP’s sustained-release, it is necessary to design a magnetic nano-carrier for CDDP with magnetic targeting function to reduce the damage of CDDP to normal tissues in vivo and improve the therapeutic effect of cancer. Carboxymethyl chitosan (CMCS) is used to directly coat oleic acid (OA)-modified Fe3O4 nanoparticles (OA-Fe3O4 NPs) to create the nano-scale CMCS magnetic nanoparticles (CMCS/OA-Fe2O3 NPs), and CDDP loaded magnetic nanoparticles (CMCS/OA-Fe2O3 NPs/CDDP) are prepared by the bonding interaction between carboxyl groups on the surface of CMCS and the anticancer drug CDDP. The magnetic drug loaded nanoparticles are characterized, and the results show that the magnetic nanoparticles are successfully embedded in CMCS and loaded with CDDP, with the drug load of 43.65 ± 2.37%. MTT assay, flow cytometry and invasion assay are applied to evaluate the inhibitory effect of magnetic drug loaded nanoparticles to nasopharyngeal carcinoma (NPC) cells HNE-1. The results suggest that the magnetic drug loaded nanoparticles successfully prepared have significant inhibitory effect on HNE-1 cells in vitro. Therefore, the magnetic drug loaded nanoparticles prepared have a good therapeutic effect on NPC.