Abstract: In the optical and synthetic aperture radar（SAR） image registration,the common features are difficult to obtain because of different radiometric and geometric properties.Meanwhile,the large scene images are time-consuming.For solving above problems,a fast optical and SAR water image registration method is proposed based on second Otsu image segmentation and scale-invariant feature transform（SIFT）.Firstly,wavelet transform of the optical and SAR image is applied to reduce the amount of data and the interference caused by small targets and noise.Then,in order to solve the problem of "over-inspection" after the Otsu segmentation,the second segmentation is used to achieve more accurate water segmentation.Finally,the mismatch features are eliminated by improving spatial consistency criterion and random sample consensus（RANSAC）.The experimental results show that the proposed method can effectively increase the accuracy of optical and SAR image registration and the computation efficiency.