Abstract: The software for welding heal cycle was developed successfully, based on some classical mathematic models and measured data and programmed appropriately by LabVIEW7.1. It is available to plot the curve of welding heat cycle conveniently and quickly so as to reflect and describe quantitatively the main influencing factors on the parameters of heat cycle and the correlation among them. This software comprises 7 kinds of welding methods and each of them is based on its own mathematic model and applies to relevant field. It can support 10 passes at most in the simulation of welding heat cycle, and the software interface is simple and easy to operate. By virtue of its stability, reliability and convenience, the software has been applied to MMS-200 thermal simulator.