Sensors are used more and more widely today. It can get valuable images through multi-sensor fusion technology. The paper designs an image security method for multi-sensor fused image. It includes keys generation, permutation, diffusion and decryption. Using six decimal numbers it can get three keys in keys generation part. The process of permutation used a new chaotic map to shuffle positions of image pixels. The process of diffusion used classic chaotic map to flat the histogram of the ciphered image. Decryption process is the reverse process of encryption process. The results prove its validity. It also show it can be used in real-time information protect for fused image.