Abstract: Microwave staring imaging as a new radar imaging mode, depends on antenna sensor radiating random signal respectively and spatial-temporal two-dimension random radiation field is formed. The received echo signal and pre-stored random radiation field are processed and the image is obtained. Due to the problem of strong correlation for electromagnetic signal, the scatterer point sidelobe is very high after directly correlated processing. To solve the proposed problem, this paper proposes a new method, which is based on Schmidt and Bjorck-Schmidt orthogonalization of the pre-stored random radiation field. The correlation of random radiation field between different scatterers is reduced by these two methods and the sidelobe of scatterer is suppressed. The ratio of signal-to-noise for processed image is enhanced. Finally, the fine focused image is obtained. The comparison between signals orthogonlized by Schmidt and Bjorck-Schmidt is shown in this paper and the characteristic of the pre-stored random radiation field is analyzed. Simulation experiments show that the proposed approach is feasible.