The invention discloses a full-automatic assembling-welding system for an electric conduction assembly of a low-voltage plastic-shell circuit breaker. A rotating disc assembly is arranged on a horizontal table facet and comprises an inner disc and an outer rotating disc. The lower end of the inner disc is connected with a scale division mechanism. A first driving mechanism, a second driving mechanism, a third driving mechanism and a fourth driving mechanism are arranged on the upper surface, close to the outer edge, of the inner disc. Twelve clamp assemblies with the consistent structure are uniformly arranged on the outer rotating disc along the circumference. The twelve clamp assemblies are uniformly arranged as twelve rotating stations and are in one-to-one correspondence with feeding mechanisms, discharging mechanisms, a welding mechanism and a detector which surround the circumference of the rotating disc assembly. The structure is compact, the working efficiency is high, and the welding quality of a product is stable.