With the widespread adoption of computers and the internet, we are in the midst of an information explosion. Computers have become essential for every household, used for entertaining, working, learning, and practically anything else. Using the computer as a tool to learn english has become common. Not only can the effects of learning be seen quickly, but also errors can be found and corrected immediately. Learning english with the assistance of a computer has become an inevitable trend. Outside of language, Computer Assisted Instruction (CAI) techniques have been adopted by teachers in many other fields. CAI systems are usually developed step by step. The entire teaching system is programmed gradually and precisely to satisfy the different requirements of users of all ages. Alternatively, different programs are devised for different purposes, each of which is specially developed for a specific group or a single purpose so that they are more user-friendly and users can better learn and obtain the information they want. With the assistance of computers and the internet, this kind of cooperative learning aimed at using language for communicating effectively will become more interesting and attractive. And teachers may devise a variety of teaching programs according to students’ level of familiarity with the internet. To study the relationship between computer-assisted instruction and english learning achievements, a qualitative study was conducted through in-depth interviews with english teachers. The researchers interviewed three english teachers ages 30 to 45 at a private university in Taipei County, all good at CAI. The study found that to keep up with the trend of CAI and globalization, teachers have to have various skills. They should have relevant knowledge of science and technology to use the internet to design different class activities competently. In addition, teachers need to understand students’ learning styles, and they must care about students’ learning processes.