The invention discloses a device for 
welding stainless steel by resistance heat as well as stirring and friction, comprising an 
electric power source, a 
transformer and a stirring head, wherein, two output terminals of the 
electric power source are connected with the input terminal of the 
transformer by an electric cable, one output terminal of the 
transformer is connected with a 
cushion plate by the electric cable, the 
cushion plate is used for placing work pieces, the other output terminal of the transformer is connected with an electric 
brush by the electric cable, the electric 
brush is contacted with a 
copper ring arranged in a groove at the upper end of the stirring head. When the device of the invention is adopted for 
welding, the transformer is adjusted to form 
low voltage heavy current; driven by an 
electric motor, a mixing needle is screwed in the space between two work pieces, a 
low voltage heavy current circuit is conducted and generates relatively 
high resistance heat on the work pieces, materials at the 
welding lines are plasticized under high temperature effect of the resistance heat and friction heat, and welding lines form at the rear part of the mixing needle. Stirring 
friction welding of stainless steel can be realized, abrasion of the stirring head can be reduced, weld length of the stirring head can be increased, service life of the stirring head can be prolonged; in addition, the device of the invention has simple structure and relatively low cost, and is easy to manufacture.