Abstract: Based on theories of fluid dynamics and heat transfer, a transient three-dimensional model of TIG weld pools is established, in which Gaussian distribution is used to describe the heat flux source of arc.Many factors are considered in the model including the convective heat transfer of liquid metal and the heat conduction of solid metal, latent heat in welding process, the turbulence characteristics of welding pool fluid, material thermo physical properties as the function of temperature and so on.The enthalpy-porosity technology is adopted to solve the problem with workpiece phase transformation.The graphics results of weld pools and the variation of shape parameters with time are given by using FLUENT RNG k-ε model to calculate the TIG wielding pool.The experiments show that the calculated results agree well with measured value.