In this paper, normalized difference cloud moving index ( NDCM I) is put forw ard by analyzing the remote sensing data every 15 minutes. By applying NDCM I, the detection of low cloud, thin cloud and the edge of moving cloud can be enhanced. We proposed a dynamic threshold method w ith NDCM I for preliminary cloud detection, and then through the preliminary results, w e proposed a novel cloud detection method based on back propagation neural netw ork ( BP-NN) . The experimental results show that the proposed method can eliminate the subjectivity in threshold selection, and can achieve better cloud detection results for remote sensing image in complex situations.