Abstract: Radon-Ambiguity Transform (RAT) is a good tool for detection Linear Frequency Modulated (LFM) signal in low Signal to Noise Ratio (SNR) condition. But in multi-LFM signals condition, Radon-Ambiguity transform of the strong LFM component has strong suppression effect on that of the weak LFM component. Moreover, RAT can not distinguish LFM signals with same frequency rate but with different initial frequency. A method named as time frequency representation basing on recursive filtering Radon-Ambiguity transform algorithm is proposed for solving this problem. The merit of de-noising and cross terms suppression of this method has been illustrated by computer simulation in low SNR condition.