The proliferation of “low, slow and small” UAVs (unmanned aerial vehicles) poses a serious threat to flight safety in airspace. Accurate analysis of the characteristics of UAV echo signals is of great significance for the detection of non-cooperative UAVs. Based on the time-domain integral echo model of rotor UAV target and the principle of cepstrum algorithm, the frequency-domain expression and cepstrum expression of echo signal were derived, the corresponding relationship between echo signal parameters and frequency-domain and cepstrum characteristics was analyzed, and a parameter estimation method for UAV echo signal was proposed, and the effectiveness of this method was verified by simulation and measured data. The results show that, it can estimate the bandwidth and rotation frequency of UAV echo signal more accurately and provide an important reference for target detection and recognition of UAV.