Abstract: Source number estimation directly affects the performance of high resolution direction of arrival. To improve the performance, this paper proposes a method based on fuzzy C-means(FCM) clustering. Eigenvalues of covariance matrix and the difference of them are utilized as the indices of targets. As well, radii of Gerschgorin disk based on unitary transform and the difference of them are also employed. To improve the performance of the proposed method, probability of fault tolerant is introduced. The simulations with different styles of noises indicate that it has a good performance on estimating source number.