Abstract: In this paper, the observability and performance of the approach for estimating the miss distance parameters of a target by sequential Doppler frequency were studied. Under the assumption that the missile's trajectory near its target was relatively in uniform rectilinear motion, the global observability of the approach was proved. Then when estimation errors of Doppler frequency exist to meet zero-mean independent Gaussian distribution, the performance analysis was carried out using both the symbolic and numeric Cramér-Rao lower bound (CRLB), the correctness of which then was proved to be correct. Finally, the estimation performance of different missile miss distance in certain system parameters conditions was given through numeric CRLB. This provides theory references for the miss distance measurement of this method.