This paper proposes an edge-based superpixel similarity measurement, which globally evaluates the similarity between superpixels by binary edge maps. The basic idea is to assess whether the superpixels are surrounded by the same edges. To this end, we first describe the edge spatial distributions by directional regions and then use the directional regions to represent the surrounding relationships of superpixels and edges by their traverse relationships, which form the histogram feature. Finally, the similarity is simply calculated by the distances between the features. To verify the proposed similarity measurement, we use our global similarity measurement to perform superpixel clustering. Two clustering methods, the directed graph clustering (DGC) and spectral clustering (ultrametric contour map) are combined to achieve the clustering process. The combination of our global similarity measurement and DGC to form a new three-layer-based superpixel generation method, which can quickly generate the superpixel from edge maps, is highlighted. We verify the global similarity measurement by the BSDS500 dataset. The experimental results demonstrate that the proposed global similarity measurement can improve the clustering accuracy in terms of larger intersection-over-union-criterion-based values. The code can be downloaded from https://github.com/FanmanMeng/Superpixel-Similarity-Measurement .