Aiming at the problems of high system cost, complex ranging process, low ranging accuracy, and limited measurement distance in commonly used methods for ground fixed point distance measurement journals, a variable frequency microwave ranging system based on a dual transponder architecture is proposed in this letter. The system uses carrier dual transponder as an active forwarding architecture, utilizing the digital phase‐locked loop to obtain the high‐precision phase difference between two signals, and resolving the ambiguity through microwave frequency sweep within a certain range. The simulation results show that the system can quickly obtain the unambiguous distance between two fixed points, besides, driven by a high‐stability crystal oscillator, submillimetre accuracy can be achieved in km‐level ranging. A variable frequency microwave ranging system based on a dual transponder architecture is proposed for ground fixed point ranging. In this system, a dual transponder architecture is adopted to obtain high‐precision carrier phase measurement information, and a carrier frequency sweep algorithm is used to solve the problem of phase ambiguity. The experimental results demonstrate that compared to traditional ranging methods, this system can effectively improve ranging accuracy and measurement upper limit at low equipment costs.