The invention discloses a novel mobile rotary welding jig device. A rotary welding jig device is arranged in a mobile device for increasing the flexibility of the rotary welding jig and enabling the rotary welding jig to move easily. And the rotary welding jig is further provided with connecting pins and casters for switching between a moving state and a machining state at any time. According to the novel mobile rotary welding jig device, the jig device not easy to maintain is transferred to the outside of the jig for being easy to maintain, a standard part is used for rotating a cylinder connector for replacing the part quick for accordingly improving the replacement rate and reducing the labor intensity of maintenance workers, and meanwhile, a gas channel system is reliable in tightness for reducing the air leakage and the energy loss.