Automatic gain control (AGC) system is widely used in communication and radar receivers. When the dynamic range is wider more than 60dB, it is necessary to select AGC system with wide dynamic range to ensure or expand the index. This paper introduces the composition of the AGC system, a design flow and composition of digital AGC with large dynamic range in communication equipment are presented, and the implementation method based on FPAG is also provided. By sampling and processing the received data, this method can achieve wide dynamic range gain adjustment in real time and effectively.