Abstract: The machine translation（MT）and computer-aided translation（CAT）strongly improve the translation efficiency. Under the condition of disadvantage of theory and technology in machine translation，the CAT becomes a valid choice for translators，and there are several application software products coming out. The core technology of CAT is translation memory（TM），and the core modules are TM system，terminological data bank，alignment tool，project management system and so on. Based on the principle and feature of CAT，this paper analysed the core technology and core modules of CAT， introduced the main stream CAT software， and provided references for application and popularization of CAT tools.

Key words: machine translation, computer- aided translation, translation memory, core modules, terminological data bank, alignment tool, project management system