To separate the required target signal from the complex echo signals, the paper proposes a method on multi-target signals separation which is suitable for linear frequency modulation (LFM) radar systems and separates the target signal by filtering the echo signals from three aspects: distance, velocity and azimuth. The signal separation method adopts adaptive minimum variance distortionless responses (MVDR) filter which filters the multi-target echo signals in space, thus the required target signal will be effectively separated. Simulation on echo signals of linear frequency modulation (LFM) radar shows the feasibility of the proposed method, thus providing a valuable scheme for the development of target recognition devices and interference suppression.