In the face of the widespread use of the lime precipitation process for arsenic removal in the smelting of arsenic-containing minerals, the soundness and resourcefulness of calcium arsenate is being given increasing attention. In this paper, we investigate the preparation of metallic arsenic and regeneration of calcium oxide by the reduction of calcium arsenate by carbon thermal roasting. Thermogravimetric analysis shows that the weight loss of calcium arsenate mixed with carbon powder is divided into three stages, with stages one and two being the water loss process and stage three being the carbon reduction of calcium arsenate to produce CaO and arsenic vapour. And it was found that the phase three reaction mechanism could be explained by using the phase boundary reaction kinetic model. The results of the single-factor experiments showed that the arsenic volatilisation rate was as high as 99.94% at a temperature of 1000°C, a carbon incorporation factor of 1.4 and a constant temperature of 60 min. The characterisation of the products in the reaction system by X-ray diffraction (XRD) and scanning electron microscope energy spectrometry (SEM-EDS) showed that the arsenic products were mainly flake metallic arsenic and powder indeterminate arsenic, and the roasting residue was CaO.