Abstract: Optimizing the shape of solder joints in SMT (Surface Mount Technology) is an important way to improve the reliability of the joint. A method to cut SMT solder joints and obtain the profile of any section in solder joints is put forward according to the results of predicting the shape of SMT solder joints, and the meshes for finite element analyzing the mechanical behavior of solder joints are created. Thus, the model for predicting 3-D(three dimensional) shape of SMT solder joints is combined with the model for analyzing the reliability of the joint. A visual program is built to cut solder joints and display sectional profiles in multiple windows. The program is interfaced with the program Evolver which is used to predict the global shape of solder joints, and sectional profiles of solder joints can be obtained quickly and observed directly. The 3-D characteristic of the shape of SMT solder joints is analyzed through the visual program, and the different section shape of the solder joint is given with the variation of solder volume.