One of the indispensable technologies in this booming era of self-driving technology is the development of by-wire control systems. How to accurately, quickly and stably execute the commands of the decision-making and control center and feedback status to the self-driving system depends on a by-wire control system necessary to be considered during product design and development. The by-wire control system is like the human hands and feet. If there are many excellent algorithms in the brain but we cannot execut them, there is no way to be discovered by others. Therefore, the by-wire control system is the most basic and important equipment to develop self-driving technology. This article will introduce the design of the braking system in the by-wire control system for a self-driving vehicle and the autonomous emergency braking technology achieved by using this system.