Abstract: Automatic gain control circuit is one of the key control circuits in radar receiver modules for improving receive dynamic range. According to the technical requirements of a certain type of radar IF receiver module, an Automatic gain control circuit have been designed in this paper. The difficult of the design is detecting pulsed power accurately on different pulse width and repetition periods condition. To resolve this problem, It takes advantage of the pulse edge to touch off data acquisition and judge pulse power with logarithmic detector based on FPGA and ARM in this paper . Experimental results show that the circuit completes the automatic gain control in 1ms as well as the input dynamic is range of 60dB (-50dBm～+10dBm).