A time delay method estimated by the second correlation has been raised compared with the low precision of traditional methods. This method is based on the model of arbitrary multi-sensor array in space and the passive localization algorithm. Firstly, it makes an auto-correlation of the signal in order to improve the SNR. Secondly, it correlates the auto-correlation and the cross-correlation to get the time-delay estimation. It has been verified in theory and by experiments that this method can restrain the impact of noise to signal obviously and improve the precision of time-delay estimation compared with the generalized cross-correlation。