Abstract: A software consisted of pre-processing, post-processing and solidification cracks predicting subsystems is developed, which can simulate and predict the weld solidification cracks with three dimensional FEM.The pre-processing helps users to choose the workpiece, to input the thermal-mechanical properties of materials and welding parameters, to set boundary conditions, and to automatically generate command streams of MSC.Marc to create process files for final FEM calculation.Furthermore, system can transfer the process files to software package of MSC.Marc to complete the calculation of thermal, strain and stress distributions in background.Therefore, the simulated results are prepared for the post-processing.