Component Object Model(COM) technology is the base of many softwares about Microsoft, it provides a wide way to access the component object overriding the Programing language, OS(Operating System) and Net, and make it possible to integrate a software by components. This article disserted its technology connotation and how to apply it in practice. Software developers have a eager desire that there was a technology which made them to develop big and complex application system easily. They hope to use the exis...