The invention discloses a fully-automatic assembling and welding system for a conductive assembly. The fully-automatic assembling and welding system comprises a rotary plate assembly on a horizontal table, wherein the rotary plate assembly comprises an inner plate and an outer rotary plate; the outer rotary plate is equipped with an indexing mechanism; two top-pressure air cylinders are arranged on the upper surface, close to the outer edge, of the inner plate; twelve clamp assemblies which are consistent in structure are uniformly arranged in the peripheral direction of the upper surface of the outer rotary plate; the twelve clamp assemblies are used as twelve rotary stations; an oil cup loading mechanism, a lower gasket loading mechanism I, a lower gasket loading mechanism II, a coil loading mechanism, an upper gasket loading mechanism, a magnetic yoke loading mechanism, a soldering mechanism and a finished product moving mechanism are separately arranged outside the twelve stations of the outer rotary plate; and an oil cup detector, a lower gasket detector, a coil detector, an upper gasket detector and a magnetic yoke detector are separately arranged at the periphery of the outer rotary plate. The invention further discloses a fully-automatic assembling and welding method for the conductive assembly. The device and the method disclosed by the invention are compact in structure, are reliable in work and are high in welding quality.