The sodium roasted-acid leaching tailing (SRALT) of vanadium slag with a certain amount of vanadium exhibits potential environmental risk. To investigate the leaching behavior of vanadium from the SRALT, neutral batch leaching tests were performed. The evolution of vanadium concentration, pH, redox potential (Eh), dissolved oxygen, and conductivity as a function of time was measured. Pourbaix diagrams of V–H₂O system with different vanadium concentrations were obtained to identify the ionic speciation of vanadium in leachate. X-ray diffraction, X-ray photoelectron spectroscopy, field emission-scanning electron microscopy, and thermogravimetry–differential scanning calorimetry analysis were conducted to investigate the mineralogical evolution of the SRALT during the leaching process. It was found that the major minerals of the original SRALT are titanomagnetite, spinel, olivine, and augite. The valence states of V existing in the original SRALT are V³⁺ and V^5+. The pH and Eh values of the obtained leachates are 10.00–10.58 and (-43)–(+67) mV, respectively. In this pH and Eh region, the released vanadium is mainly present as HVO₄^2-. The FeOOH and CaCO^₃ would form during the leaching process. The HVO₄^2- would be mainly adsorbed by the FeOOH and slightly incorporated into the CaCO₃, resulting in the decline in the vanadium concentration. The vanadium concentration above 27 mg L^-1 and the dissolved oxygen value below 5.0 mg L^-1 can be obtained after a short leaching period. As a V(V)-releasing and oxygendepleting substance, the leaching toxicity of the SRALT should not be ignored.