Abstract: For the sake of assisting PCB designer to find the source of crosstalk signal according to the frequency characteristics of crosstalk signal, a new method of recognizing PCB crosstalk signal frequency is put forward. It’s principium is applying singular recognizability of wavelet function to recognize rising edge (or falling edge) of crosstalk signal from interfered signal, then confirming frequency of crosstalk signal directly according to rising edge (or falling edge) of crosstalk signal. The results of simulator show that the crosstalk signal frequency obtained from this method is consistent to practical frequency.