Abstract: We propose a new DiffS algorithm which is suitable for detecting difference between different version SVG/XML format maps.The algorithm reduces the sum of nodes and levels of parsing tree by defining macro element.By defining dynamic array as data structure and then using top-down level-order traversal approach to match two different version parsing trees,the result of DiffS is an edit script which records the update operations from the first version of SVG map to the second version.The algorithm time complexity of DiffS is low.The application verification shows that the algorithm is effective.