Abstract: The thin-walled structures of high-strength alloy have serious distortion and high susceptibility to welding hot cracking.To solve these problems, a new type of pulse electromagnetic force generator was developed to control welding stress in virtue of the pulse electromagnetic force during welding, without direct contacting the weldment.The magnitude of the force can be controlled by changing voltage of energy storage capacitor, while the frequency of the force can also be set in 10-90 Hz.The generator is characterized by simple structure of main circuit, convenient adjustment and excellent reliability.Simulation and experiment results indicate that the generator satisfies the requirement of design.The fishbone cracking test with pulse electromagnetic force confirms that the pulse electromagnetic force is capable of controlling welding hot cracking.