Single-source shortest path problem is one of basic researches in graphic theory. Considering the similarity and easy transferability of data structure between graphic and tree, an improved algorithm solving this problem is put forward based on the technology of XML. Using XML structure, this algorithm transfers a graphic to some tree, and analyzes each edge in this tree to adjust the best distance between other vertices and the source vertex. With basic controls used in the execution of this algorithm to simulated the process, and experimental results show that this new algorithm is much more efficient, and more flexible, and easy to understand and good to practical applications.