Radio frequency interference (RFI) often causes great trouble to HF radars.We propose a novel method for RFI suppression based on the discrepancies of the time-frequency distributions of the RFI and the target signals.The method suppresses RFI effectively while hardly brings any loss to the target signals so that the qualities of the echo range-Doppler spectra are greatly improved and the anti-jamming abilities of the HF radars are greatly enhanced.The method can also be regarded as a soft realization of the real time radar frequency selection.