The composition, welding application value,welding process test and practical welding application of a single power source twin-wire system（Deepen Twin） are introduced and analyzed. Deepen Twin is composed of welding power source, twin-wire feeder and twin-wire welding gun,which is simple and easy to be operated. Deepen Twin can be used for manual welding and automatic welding of the special machine and robot. And it can realize the free switch between single wire and twin wires, and can be used for backing welding with single wire and welding with twin wires, high current and high cladding rate, and the maximum cladding efficiency can be increased by 50%. The twin wires form a single wide arc, thus the arc heat distribution is more uniform, undercut is not easy to occur in weld, and there are low spatter, good weld forming and no arc interference, the quality of weld obtained by twin-wire welding is higher than that by single wire welding, which is a new high-speed and efficient welding solution.