Abstract: Three-dimensional quasi-steady temperature field numerical simulation of deep penetration in electron beam welding of Ti₃Al intermetallic compound was conducted on condition of moving heat soure using modified double ellipsoidal mathematical model on basis of finite element method.In the model,the relationship between deep penetration and electron beam process parameter,material thermal physical properties and the convection and radiation effect,the latent heat of phase transformation,the temperature dependence of thermal physical properties and the convection heat transfer in the welding pool were considered.The simulation results showed a good agreement with the experimental results to confirm adaptability of the new model.