Given two ordered,labeled trees β and α,to find the distance from tree β to tree α is animportant problem in many fields,for example,the pattern recognition field.In this paper,a VLSIalgorithm for calculating the tree-to-tree distance is presented.The computation structure of the algorithmis a 2-D Mesh with the size m*n-and the time is O(m+n),where m,n are the numbers of nodesof the tree β and tree α,respectively. Given two ordered, labeled trees β and α, to find the distance from tree β to tree α is animportant problem in many fields, for example, the pattern recognition field. In this paper, a VLSI algorithm for calculating the tree-to-tree distance is presented. The computation structure of the algorithmis a 2-D Mesh with the size m * n-and the time is O (m + n), where m, n are the numbers of nodes of the tree β and tree α, respectively.