To support strong interference signal input under “navigation warfare” scenarios, navigation receivers are requested for increasing dynamic range in analog channels. Under the given constraint condition of signal to noise ratio deterioration, a two-dimensional curve model to offer a method for dynamic range optimizing and stage gain design was put forward by the legacy analysis method. However, this method was only applicable for the AGC(automatic gain control) circuits that the output power was basically stable. A solving model involving the three-dimensional curve based on the extra parameter called the rollback value of the AGC output power was put forward. The model revealed the relationship between the circuit parameters and the dynamic range of analog channel and it is suitable for the AGC circuits with variable output power, which can achieve a larger dynamic range. To reduce the complexity of the parameter calculation in the three-dimensional model, the complex numerical solution to linear equation solution according to the features of pure attenuation network was simplified. This simplification can substantially reduce the design complexity. Test results of dynamic range are in good consistence with the expectation in practical designs, which proves the accuracy of the analysis model.