The core of requirement analysis is to fully and accurately obtain customer requirements from requirement data. Nowadays, with the development of computer technology and e-commerce, a large number of personalized electromechanical products requirement data appear on various network platforms. The traditional requirement analysis methods are difficult to deal with it. This paper proposed a method of requirement identification and disassembly of electromechanical products based on domain knowledge network. The existing electromechanical domain knowledge is reused to identify and disassemble the requirement text expressed by the customer in the unstructured form of natural language. Based on this method, this paper developed a computer-aided requirement analysis tool, which can assist designers to quickly clarify the requirement.