Abstract: In order to obtain a welded joint with good performance, in the development environment of MATLAB App Designer, based on the CCT map of the low carbon steel alloy welding, an App that can reflect the welding process parameter, weld cooling time, and welding heat-affected zone structure and performance is developed. Four main modules of welding process parameter, welding material and CCT map, tissue ratio, metallographic diagram and hardness, and imported temperature field data are established in the App. Based on the welding CCT map, the software uses interpolation method to calculate and predict the structure ratio, metallographic map and hardness of the welding heat-affected zone. The 15MnVR steel is taken as an example for calculation and analysis.