Abstract: Based on the APDL command flow of ANSYS finite element software to calculate the temperature field, residual stress and lateral shrinkage of the T2-Y/Q345 heterogeneous flat plate butt joint. The temperature, residual stress and lateral shrinkage of the welded joint are measured. The results show that compared with the T2-Y side, there is a larger temperature gradient on the Q345 side. Along the weld direction, the lateral stress and longitudinal stress on the T2-Y and Q345 sides are double hump-shaped and cap-shaped, respectively. On the upper surface of the central interface of the weld, the stress distribution of the longitudinal stress and the lateral stress in the weld and the heat-affected zone are discontinuous, and there is a large stress gradient on the Q345 side. In addition, the maximum lateral shrinkage of T2-Y/Q345 is at the middle part of the welding seam, which gradually decreases towards both ends. The numerical simulation results are basically agreed with the test results, which verifies the reliability of ANSYS finite element calculation.