Abstract: The signal power is very weak in navigation receivers, usually lower than noise. The fluctuation of the input power level is usually caused by jammers. According to this phenomenon, the noise figure of the receiver is required not to deteriorate in the presence of jammers. One of the factors in deteriorating the noise figure of the receiver is the noise figure of the RF channel. Aiming at maximizing the dynamic range of the RF channel, this paper analyzes the method of calculating the maximum dynamic range of AGC circuit and the gain of each circuit part given the bound of noise figure deterioration, and further develops a more brief method for a particular kind of AGC circuit made of resistance network. Lastly, the paper gives an example of the dynamic range design of this kind of AGC circuit, and the measured results of the example agrees well with the designing anticipation. The method in this paper can be used not only in navigation receivers, but also in various kinds of receivers.