A new preprocessing method used for target detection in hyperspectral imagery was proposed. This preprocessing method can increase target spectra accuracy, so the performance of the target detection methods can be improved. By using the target spectra gotten from the laboratory and field as references, the proposed method extracts independent components, which are the closest to the references, from the hyperspectral imagery by means of independent component analysis with references (ICA-R). Then, these independent components are used as target spectra in the following supervised target detection methods. Experimental results on both simulated and real hyperspectral data demonstrate that the proposed method can get more accurate target spectra, which obtains much better performance of target detection.