Abstract: Disulfiram (DSF) is a traditional anti-alcohol drug, but it was recently found that DSF has strong inhibitory effect on the growth of a variety of cancer cells. However, its clinical application is greatly limited due to its poor solubility, instability in gastrointestinal tract and short plasma half-life. In this study, DSF is fabricated into nanosuspensions with the aim of trying to solve these problems. DSF nanosuspensions (DSF-NSps) were prepared by the anti-solvent precipitation method under ultrasonication, and the suitable stabilizer was screened according to the size, polydispersity index (PDI), and zeta potential of the resultant nanosuspensions, along with their particle size change during the storage at room temperature. The particle size, PDI, and zeta potential of DSF-NSps were determined using dynamic light scattering method, while the morphology of DSF-NSps was observed by transmission electronic microscope (TEM). The stability of DSF-NSps in media was examined according to their particle size change in different physiological media. The concentration of DSF was measured by HPLC assay. The in vitro drug release was evaluated on basis of dialysis. MTT assay was employed to evaluate the in vitro cytotoxicity of DSF-NSps against cancer cell lines. The 4T1 tumor-bearing mouse model was used to evaluate the in vivo therapeutic efficacy of DSF-NSps. All the animal experiments were acquired according to the Regulations for Animal Experiments and Guidelines for Ethical as defined by Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College. As a result, the combinational use of soyabean lecithin (SPC) and D-alpha tocopherol acid polyethyene glycol succinate (TPGS) was determined to best stabilize DSF-NSps when the ratio of DSF-SPC-TPGS was 24:20:4 (weight ratio), with small particle size and good storage stability. The resultant DSF-NSps showed a regular spherical morphology and drug loading content of (45.36 ±2.09)%, with average particle size of 175.00 ±0.75 nm, PDI of 0.24 ±0.07 and zeta potential of -14.3 mV. DSF-NSps displayed good particle size stability in a variety of biological media including phosphate buffer saline, normal saline, 5% glucose, artificial gastric fluid, artificial intestinal fluid and plasma, which would meet the demand of both intravenous and oral administration. The in vitro study demonstrated that nano-encapsulation greatly increased the stability of DSF in aqueous media, DSF-NSps exhibited sustained release of the encapsulated drug and significantly inhibited 4T1 cells compared to free DSF (IC₅₀, 1.07 vs 5.53 μg·mL^-1, P<0.01). DSF-NSps showed a good dose-response relationship on the 4T1 tumor-bearing mice with the tumor inhibition rates at the three doses being 80.22%, 75.14% and 66.10%, all higher than that of paclitaxel injections (55.01%, P<0.05). The in vivo biodistribution study displayed that DSF-NSps were mainly distributed into liver, spleen and tumor. In sum, disulfiram nanoparticles could be expected to provide an effective anti-cancer drug for the treatment of breast cancer.