This paper first presents the definition of computer assisted translation (CAT), usability index, user experience. Combining quantitative analysis method and questionnaire investigation method, this paper evaluates the application of CAT based on usability index and user experience. Research hypothesis, research design, model architecture and hypothesis validation model are used to verify the impact of usability index on users’ choice of CAT software. Finally, the paper investigates the application of CAT software in English translation teaching for college students in China, and collects and analyzes the attitudes of teachers and students to CAT. The paper studies the contradiction between user demand and CAT software supply from the perspective of the usability of CAT so that to help the user to choose appropriate CAT software. The research on the application of CAT in English teaching has a scientific effect on the promotion of CAT in English translation.