The invention discloses a rapid prototyping device of metal or a metal matrix composite. The rapid prototyping device comprises a machining platform and a base plate, wherein the base plate is located on the machining platform. An immediate-cleaning wire brush mechanism and an electricity-conductive roller of a resistance welding machine are arranged above the machining platform; the immediate-cleaning wire brush mechanism comprises a rolling wheel and a first wire brush which are located above the base plate and arranged adjacently and a second wire brush arranged to be tightly attached to the base plate; and the electricity-conductive roller, the rolling wheel, the first wire brush and the second wire brush can all conduct rotational motion on the corresponding positions which can be adjusted according to the thickness of stacking of metal foil pieces, and the machining platform can conduct plane movement. Meanwhile the prototyping method is further disclosed, the immediate-cleaning wire brush mechanism conducts surface-cleaning on the metal foil pieces before welding, later the electricity-conductive roller conducts interlayer-welding on the foil pieces under a certain pressure, and finally the additive manufacturing process on the metal base plate is achieved. According to the rapid prototyping device of the metal or the metal matrix composite and the prototyping method thereof, the prepared parts are high in strength and good in density, and the rapid prototyping device and the prototyping method are suitable for quantity production of part rapid prototyping.