Abstract: A new method for estimating wideband source numbers is proposed by utilizing the matrix of cross-covariance functions of different frequencies. It is proved that the Gerschgorin disk of narrowband sources with some modifications can be used to solve the matrix to obtain the estimation of the number of wideband signal. The performance of correlation wideband signals and noncorrelation wideband signals are analyzed. Results prove that the method can be used in such a situation which CSSM methods are useless. The stimulation validates this method not only can be used under array element less than wideband signal numbers but also have small computation burden.