The purposes of this study were to investigate the safety of Dextran coated GoldMag Nanoparticles (DGMNs) as a drug carrier of the chemotherapy compound doxorubicin (Dox) in vitro and the acute toxicity of Dox-conjugated DGMNs (Dox-DGMNs) in vivo, and then the anti-tumor activity of Dox-DGMNs were assessed in vitro and in vivo.Firstly, Dox-DGMNs were synthesized successfully.Drug studies in vitro showed that Dox could bind effectively to DGMNs and was steadily/controllably released from the particle surface in physiological conditions.Secondly, cytotoxicity was assessed by modified MTT assay.The results suggested that DGMNs had lower toxicity and better biocompatibility and Dox-DGMNs combining with external magnetic field (EMF) to human liver hepatocellular carcinoma cell line (HepG2) had better therapeutic effect compared to Dox.Thirdly, the results for DGMNs showed that they were safety as targeted drug delivery system carrier according to State Food and Drug Administration (SFDA) regulations.The acute-toxicity study for Dox-DGMNs illustrated that they were low toxicity when the dose was less than 500 mg/kg body weight (BW).The calculated acute LD50 values that we determined for Ⅳ routes of drag delivery with Dox-DGMNs and Dox were 513.3 mg/kg BW and 15.60 mg/kg BW, respectively.It is obvious that Dox-DGMNs significantly decrease systemic toxicity and prolong the half-life.The organs (tissues) coefficients results demonstrated that there were no damage to liver, spleen and lung when the dose of the Dox-DGMNs is less than 500 mg/kg BW.Histological studies results are consistent with that of organs (tissues) coefficients.All these show that Dox-DGMNs are safe in application as a drug carrier and make them ideal candidates in targeted delivery in the near future.