Welding sequence is one important factor which affects the residual stresses and distortions produced during welding, thus determines the welding quality and performance. In this paper, 3D numerical simulation of temperature distribution, residual stresses and distortions of the T-joint fillet weld with respect to the variation of welding sequence is presented. The finite element simulation involved thermo-mechanical analyses. Four welding sequences (WS) considered are one direction welding (WS-1), contrary direction welding (WS-2), welding from centre of one side (WS-3) and welding from centres of two sides (WS-4). The simulation results revealed that peak temperature achieved in the welding was greatly affected by the welding sequence and residual stress and angular distortion produced cannot both hold in minimum for a WS. The smallest residual stresses and the smallest angular distortions are related respectively to WS-2 and WS-4. The distributions of temperature, longitudinal and transverse residual stresses as well as angular distortions were also presented.