Abstract: Wide band linear frequency modulated continuous-wave radar has been widely used nowadays.However,the movement of target causes range-velocity coupling which will in trun cause the ambiguity of range profile.Through analyzing the target echo signal,a new range-velocity decoupling method is obtaind.Using the Radon-Ambiguity transform and the fractional Fourier transform,this method estimated the frequency modulation rate and the initial frequency of the echo signal,and the range-velocity decoupling was realized at last.Finally,The simulation results confirmed the validity of this algorithm.Simultaneously,the light computation load,precision and some other merits of this algorithm were disscussed in this paper.