The deep mining of electric data has gradually become a research hotspot for scholars at home and abroad, it is difficult to identify the power topology structure in the current low-voltage distribution table area due to the lack of files and circuit changes, an on-line generating method for power topology in low-voltage platform based on power measurement data was proposed in this paper.According to the principle that electric energy will generate voltage drop in the transmission process of transmission lines, this method first took the load timing sequence voltage data as the basis for classification, the nodes were clustered with K-means; next took branch as unit, creatively, the branch was divided into two types: middle branch and end branch, then calculated the input-output current of each branch and construct the current matrix at the head and end of the branch, it was considered that there is a connection between the branches which satisfy Kirchhoff's current law(KCL), at the same time, the voltage auxiliary criterion was introduced to generate the power topological relationship of the low-voltage platform area. The method presented in this paper does not require a lot of hardware devices, thus saving manpower, the example shows that the method is scientific and effective.