Abstract: The pullulanase gene TM-pulA was choosed from the extreme thermophilic bacterium Thermosipho melanesiensis (DSM12029)and cloned by using the genome purchased from the Leibniz Institute DSMZ-German Collection of Microorganisms and Cell Cultures as the template. The plasmid pET21a containing TM-pulA was constructed by restriction enzyme digestion and linking method. The recombinant plasmid was transferred into strain Escherichia coli Rosetta (DE3). After purification, the hydrolysis products were analyzed and the enzymatic properties were determined. The results are as follows:TM-pulA is a type Ⅰ pullulanase;the optimum pH is 5.8; the optimum temperature is 80℃; The half-life is 4.75 h; Mn²⁺, Co²⁺, Al³⁺, Fe³⁺, SDS and EDTA inhibit the activity of enzymes in different degrees; the value of K_m, V_max, K_cat and K_cat/K_m are 4.68 g·L^-1, 0.0085 mmol·L^-1·s^-1, 71.18 s^-1 and 15.21 L·g^-1·s^-1, respectively.