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：Dissimilar steel joints have been more and more widely used in industries in recent years. When a dissimilar steel joint with medium or thick plate is performed, a groove is usually prepared for obtaining a sound joint with full penetration. Because weld metal needs to be deposited within the groove to form the joint, it is expected that different groove shape will require different heat input and weld passes. Theoretically, different heat input and weld pass possibly have a large influence on welding residual stresses and deformation. The influence of groove on welding residual stress and deformation in a Q345/SUS304 dissimilar steel butt welded joint whose thick plate is 10 mm is investigated by means of both numerical simulation and experiment. Based on ABAQUS software, a thermal elastic plastic finite element method is developed to simulate welding temperature field, residual stress and deformation of multi-pass joint. By using the developed computational approach, the temperature fields, residual stress distributions and deformations in V-groove and X-groove Q345/SSU304 joints are calculated. The welding residual stress distribution on the surface of a joint with X-groove are obtained by hole drilling strain gauge method, while the shrinkages and angular distortions in V-groove and X-groove joints are measured by using vernier caliper and 3D coordinate measuring system, respectively. The comparison between numerical model and experimental mock-up shows that the welding residual stresses and the deformations of the V-groove joint predicted by the finite element model are in good agreement with those measured by experiment. This information suggests that the computational approach developed by this work is effective. Both the experimental and simulation results show that the longitudinal residual stress distribution is discontinuous near the fusion line between Q345 and weld metal. Besides, the region with high tensile residual stress in SUS304 side is wider than that in Q345 side. It seems that groove type has a limited influence on the peak value of longitudinal residual stress, while it has certain influence on the peak value of transverse residual stress. Both the simulated results and the measured data indicate that the transverse shrinkage and the angular distortion of V-groove joint are significantly larger than those of X-groove joint.