Abstract: A new medical image registration measure based on mutual information and mutual edge distance is proposed in this paper.It takes advantage of the information contributed by the overall intensity values of registering images as well as the mutual mean distance and mutual distance variance derived from edge distance images.It has been proven by tests that this measure inherits most merits of mutual information and additionally bears several improved attributes：the measure curves are smoother and steeper.The areas of total curves’ convergence are wider.The new measure has less extreme point and better robustness to image size.It can identify different images even if their mutual information are same.