The numerical simulation of the fillet-welded joint which is welded with the four kind of clamped methods by laser-MIG hybrid welding is researched by the SYSWELD software. The results of the numerical simulation are compared with the results of the experienced welding. The results of research show: The joint of the laser-MIG hybrid welding was simulated well by the SYSWELD software. The simulating result is deviated 10% from the result of the actual deformation. The laser-MIG hybrid welding deformation of the aluminum structure is least when the holding position is in the near weld zone and the clamps are unloaded near the room temperature.