Abstract: This paper introduces the performance characteristics of the MCU P87LPC764 as well as the design and realization of an intelligent gating system with this MCU as its heart. Also, this paper describes the main control unit and the whole design of the system, and analyzes the encryption principle of the code hopping encoder adopted by this system. At the meantime, the security performances of code hopping encoder and code fixed encoder are compared. This kind of door entry control is becoming popular, since it runs reliably and has good effect.