In order to accurately detect the coaxial cable length within 20 meters and the load types and parameters,a detection method based on Time Domain Reflectometry is designed.This method mainly uses the principle of incident and reflection,generates the signal source through the DDS signal generator.After being amplified by the two-way amplifier,the signal enters the dual directional coupler for distribution and detection.Through the phase difference between the two signals measured by the circuit,the length of the coaxial cable can be obtained by combining the frequency,and the load types and load length parameters can be inferred according to the amplitude of the measured two-way signals.The experimental results show that the measurement error of this method is not over 3%,and the accuracy meets the actual measurement requirements.