A detection algorithm of weapon concealed underneath person’s clothes based on Fuzzy C-means (FCM) clustering is presented, aiming at the problem of image fusion, for example, no protecting the personal privacy, no true color. The main idea of the algorithm is to segment and extract the shape of concealed weapon from the infrared image by using FCM clustering and mathematical morphology. And the weapon is embed into I component of visual image in HSI color space. At last, the image is converted into RGB color space. In this process, only the concealed weapon is participated in the fusion and the other parts of the human body are avoided, which protect the personal privacy. The fused image maintains true color of the visual image, and the concealed weapon is very clear. By comparison experiment, the results show that the fused image obtained from the proposed algorithm can preserve a large amount of information and have the better visual quality and objective evaluation index.