A novel anomaly detection idea is proposed to improve the detection result because of the complex background and the subpixel materials. Firstly, This method suppresses background using principal component analysis(PCA), secondly ,it extracts the endmembers by the orthogonal subspace projection(OSP), and detection the targets using spectral angle mapping (SAM) at last. And the approach is better than other two methods by comparing the ROC of three detection methods.