Abstract: YAG-MIG hybrid welding temperature field of 12 mm alluminun alloy plate was simulated using Gauss revolving heat source function by ANSYS.Convection,radiation and conduction were all considered during the simulation process.The Gauss revolving heat source was loaded through function table and its movement was realized by ANSYS Parameter Design Language.Simulated results agree well with the measured results.It concluded that Gauss revolve heat source was quite for the temperature field simulation of thick aluminum alloy hybrid welding.The comformability of experimentel result and simulation was also obtained for the 5 mm aluninun alloy plate.This methed was proved to be an efficient way to predict the shape and dimention of welded joints for YAG-MIG hybrod welding of thick aluminum alloy plate.