In this research, the high arsenic content dust of copper smelting, as a raw material, the extraction of copper and arsenic from the high arsenic content dust in the leaching system containing acidic and alkaline compounds was investigated. Meanwhile, the effects of acid/alkaline initial concentration, liquid to solid ratio, leaching temperature, leaching time on the leaching rate of copper and arsenic were studied. The optimum conditions for the leaching of high arsenic content dust and preparation of copper arsenate were determined. The results showed that acidic/alkaline leaching of high arsenic content dust was particularly effective. 93.2% of the copper, and 91.6% of the arsenic were leached in an acidic leaching process and 95% of the arsenic, while less than 3% of the copper, less than 5% of the antimony, less than 2% of the bismuth was also leached in an alkaline leaching process. A new method (the parallel flow drop precipitate method) was developed in the synthesis of copper arsenate process. The parallel flow drop method was employed to adjust the molar ratio (copper to arsenic) of the mixed solution of the acid-leaching solution and the alkali-leaching solution by taking the drop acceleration of an acidic leaching solution and an alkaline leaching solution at 10 mL/min and 12 mL/min, at a temperature of 60°C and a reaction time of 1 h. Copper arsenate was prepared by mixing an acidic leaching solution and an alkaline leaching solution. The main phases of copper arsenate were CuHAsO4·1.5H2O and Cu5As4O15·9H2O. Copper arsenate contained 30.13% copper and 31.10% arsenic.