Abstract: Carrier frequency blind estimation of phase shift keying(PSK) signals in the electronic reconnaissance is discussed and a novel blind estimation method in low signal to noise ratio (SNR) is proposed. The PSK signal is divided into some overlapping intervals of equal length. The spectral concentration measures of the signal in every interval are calculated based on the Fast Fourier Transform. Then, the grid-density clustering algorithm is adopted to process the spectral concentration measures, and the clustering result is regarded as the characteristic class. Finally, the spectrums of the characteristic class are accumulated to estimate the carrier frequency of the PSK signal. Experimental results shows that the proposed method, which can effectively estimate the carrier frequency in low SNR without any prior knowledge and is not sensitive to the coded type, is suitable for electronic reconnaissance occasions.