Nonrigid image registration technology is an important research direction in the computer field. It is widely used in medicine, astronomy, and military applications. In the process of nonrigid image registration, it is often impossible to simultaneously deal with local large and small deformations. To solve this problem, in combination with the theory of normalized mutual information image registration, an Active Demons nonrigid image registration algorithm based on mutual information is proposed herein. This algorithm improves the driving force of the Active Demons algorithm by introducing mutual information, which is used to register the image. The original image is used to adaptively adjust the normalization factor, and then the algorithm conducts test simulations on medical, natural, and synthetic images. Experiment results show that the proposed algorithm is superior to the original Active Demons algorithm in terms of registration accuracy and robustness. It can process large deformed images and retain their edge features, thereby providing better registration accuracy and visual effects.