Abstract: Panose is iso-malto-oligosaccharide contained α-1,6 glycosidic bonds, and α-glucosidase is the key enzyme to produce panose. In this study, the α-glucosidase gene in deep-sea hydrothermal vents thermophilic archaea Thermococcus siculi HJ21 was synthesized, and cloned into the vector pET29a. Then expressed in Escherichia coli BL21 and purified by His Trap HP column. The molecular weight of α-glucosidase was determined by SDS-PAGE. The enzymatic properties and transglycosylation were also investigated. The results showed that the gene of α-glucosidase was 729 bp and encoded 242 amino acids. The molecular weight of α-glucosidase was about 27.2 kDa. Its optimal temperature and pH were 40 ℃ and 6.0 respectively. When the receptor was fructose, and the ratio of fructose and maltose was 1:9, the highest yield of panose could reached 79.1% after 10 h reaction. The results provide a basis for producing high-purity panose by α-glucosidase from archaea.