Abstract: In this paper, the Spatial Spectrum Estimation, an important part of adaptive array signal processing, is used for estimating the direction of thermal radiation signal received by array. A novel method that a Spatial Spectrum Estimation method of target detection based on microwave radiation received by radiometer array is proposed. This method uses the Spatial Spectrum Estimation to achieve super resolution and the sparse arrangement of array to reduce the number of sensors. The experiment results show that the method proposed by this paper is feasible and achieves the super resolution of target detection at the meanwhile.