The invention belongs to the field of welding and discloses a laser-electric arc-magnetic field composite welding excitation moving platform. The laser-electric arc-magnetic field composite welding excitation moving platform comprises a base, a servo motor, a horizontal guide rail, a supporting platform, a ball screw mechanism, a support, an excitation coil and a clamp. The servo motor and the horizontal guide rail are installed on the base. The supporting platform is installed on the horizontal guide rail. The servo motor drives the supporting platform to move through the ball screw mechanism. The clamp is installed on the supporting platform. The support is installed on the base, and the excitation coil is installed on the support. The clamp of the laser-electric arc-magnetic field composite welding excitation moving platform can be used for accurately positioning and clamping a workpiece, and the excitation coil can be used for adjusting a magnetic field in a weld joint area; and the servo motor can ensure that the workpiece moves at a constant speed in the welding process, consistency of the size, direction and frequency of a magnetic field in an area where a molten pool is located during welding is ensured, and convenience is also provided for shooting the morphology of the molten pool through a high-speed video camera in the later period.