Abstract: An efficient algorithm for estimating the frequency/phase difference/amplitude ratio of multiple sinusoid signals is presented in this paper. The problem for estimating amplitude ratio is transformed into the estimation of phase. A specific data matrix is formed and an ESPRIT-like shift-invariance technique used to separate and estimate the frequency and phase which can be further separated for the estimation of phase difference and amplitude ratio. Computer simulation results illustrate standard deviations of frequency, phase differences and amplitude ratio estimations tend to approach zero when S/N increases. ESPRIT can be used to estimate Doppler frequency, phase differences and amplitude ratio of radar signals and on the basis of these values moving parameters of targets can be further estimated.