Abstract: The basic principle of welding with trailing rotating extrusion(WTRE) and its control effect in mitigating welding distortion are introduced.The impact of WTRE on welding hot crack of 2A12T4 aluminum alloy is investigated and analyzed.Experimental results show that with proper technological parameters,WTRE can inhibit the initiation and propagation of welding hot cracks effectively.The distance between extrusion tool and welding torch as well as the vertical force acting on the weldment are key technological parameters determining the control effect of welding hot cracking.WTRE method controls welding hot crack based on the binding to hot cracks at arc-starting end and the restraint action to externally expanded deformation of weldments.