Sound source localization is an important feature in robot audition. This work proposes a sound source number and directions estimation method by using the delay information of microphone array. An eigenstructure-based generalized cross correlation method is proposed to estimate time delay between microphones. Upon obtaining the time delay information, the sound source direction and velocity can be estimated by least square method. In multiple sound source case, the time delay combination among microphones is arranged such that the estimated sound speed value falls within an acceptable range. By accumulating the estimation results of sound source direction and using adaptive K-means++ algorithm, the sound source number and directions can be estimated.