Abstract: To recognize signals rapidly and effectively in the time-frequency domain,the concept and core function of short-time comparison distribution (SCD) were proposed for short-time signals through analyzing the short-time signal’s ambiguity function in the time-lag domain.As a result,a new approach of recognizing complex signals can be realized by selecting several short-time sections of a complex signal to be recognized and comparing their SCDs.Experimental results show that because the SCD of a short-time signal has a powerful ability in cross term suppression,the approach not only reduces the amount of calculation but also has a better anti-noise performance.