Abstract: The cracking source is the key and core in molecular beam epitaxy (MBE) equipment and surface treatment equipment. At present, it has been widely used in the compound semiconductor chip manufacturing industry. As the requirements for semiconductor performance gradually increase, semiconductor manufacturing equipment also needs continuous development. For thermal cracking sources with catalytic effects, due to the complex internal flow pattern distribution and the presence of wall-catalyzed chemical reactions, the Direct Simulation Monte Carlo (DSMC) method is applied for simulation and structural optimization. Taking arsenic/phosphorus (solid) and hydrogen (gas) thermal cracking sources as an example, this paper introduces the basic structure and principle of cracking sources, as well as their simulation methods.