Abstract: In the instantaneous polarization radar measurement system， the measurement error exists due to Doppler frequency shift for the fast moving target in order to get the polarization scattering matrix， using the up and down chips. In this paper， a new method is proposed to estimate the Doppler frequency shift of the target in  the single repetition period of signal using the up and down chirps. This paper gives the signal processing and the estimation formula of the Doppler frequency shift. Then the estimation of the Doppler frequency shift can be used for the compensation of the matched filterer to enhance the measurement precision of the polarization scattering matrix. The simulation proves the feasibility of the proposed method.