The graph isomorphism problem is to study the relationship between two graphs which seem to be different, but essentially identically. A novel algorithm based on the degree tree is proposed, where each node of the tree describes a given vertex and its neighboring information of a graph. Two vertexes in different graphs are regarded as mapping if the corresponding nodes and all their junior nodes are similar. Hence by comparing their degree trees, two graphs can be determined whether matching or not, and the mapping vertexes can be found. Experimental results show the approach’s performance.