The invention relates to a double-tube spiral water-jet propeller. A main shaft 3 and a spiral impeller 2 are arranged in the casing 1 of the propeller. The cross section of the casing 1 is in a shape of X-shaped four-way pipe, and two pipelines 7 are respectively arranged at the two axial ends. The two pipelines 7 are spirally distributed; the axial lines form included angles with the axial lineof the main shaft 3 and form a double-tube spiral channel in the casing 1. A bearing retainer 5 and a bearing 4 are respectively arranged at the two ends of the main shaft 3, and a sealing ring 6 is arranged between the bearing 4 and the bearing retainer 5. The invention adopts the matching of the double-tube spiral structure and the spiral impeller, not only has the function of a guiding groove of an axial flow water-jet propeller, but also has the function of a pumping chamber of a centrifugal water-jet propeller, and has the integrated superiority of both a high flow rate axial flow pump and a high pressure centrifugal pump, thus obtaining stronger water spraying propelling force, large potential of speeding up, and thereby a highly effective and energy-saving water-jet propulsion system.