In order to realize automatic image registration for infrared image and visible image,an image registration algorithm based on the steepest descent of the likelihood function was proposed.Image edge was selected as the registration point,and thus the image registration was transferred to edge point set registration.The likelihood function of edge sets registration was established on the basis of Gauss Mixture Model (GMM) of point sets.In order to resolve the optimum transformation parameter by using the steepest descent method,the likelihood function was regarded as objective function and the affine transformation parameter was regarded as the optimization variance.Meanwhile,the multiresolution pyramid was induced into iteration registration and the speed of registration algorithm for high resolution image was increased.The experiment results show that the algorithm can well complete automatic registration of infrared image and visual image at high registration accuracy and fast registration speed.