The influence on target detection of surface reflective character was computed and analyzed in the article. By introducing the orthogonal complement subspace projection method,the background signal was eliminated from the receiving mixture signal. Therefore the aim to compress the background signal was achieved. On the basis of the remaining signal,the matching pursuit algorithm was adopted to select the optimal wavelength bands automatically. Aiming at selecting the optimum wavelength bands was achieved and the target can be detected. The algorithm was applied to target detection out of the atmosphere. At last the relation between the wavelength band selection for target detection out of the atmosphere and the target's surface reflective character was obtained.