The invention relates to the field of purification of poly alpha-olefin reaction products, and particularly discloses a purification device and a purification method of a poly alpha-olefin reaction product. The purification method comprises: carrying out alkali washing on a poly alpha-olefin reaction product; carrying out primary oil-water separation on the obtained material; carrying out secondary oil-water separation on the oil phase obtained by the primary oil-water separation; carrying out primary water washing on the oil phase obtained by the secondary oil-water separation; carrying out primary layering on the obtained material; and carrying out secondary layering on the oil phase obtained by the primary layering, wherein the temperatures of the alkali washing and the primary water washing respectively are 60-100 DEG C. With the device and the method of the invention, the content of the water-soluble organic impurities in the obtained purification product can be less than 1000 mg/L, the content of the water-soluble inorganic impurities is less than 2 mg/L, and the content of the sodium ions is less than 1 mg/L, so that the requirements of the downstream process flow and the quality of the final product can be completely met.