A straightforward and unified approach for solving the large-scale, faulted power systems is presented in this paper. In contrast .with conventional algorithms, the various changes of topology and impedance of the systems and its boundary conditions of fault can be handled flexibility and effectively in one-step procedure by proposed method, and it is convenient to choose the computational procedure more resonable according to the situation of power systems. One of the noteworthy features of the proposed method is the natural manner to handle mutual effects, and it is easy to design programs. The calculating technique for easy-to-program is given in this paper. It shows that effectiveness of calculating large-scale faulte power systems with topology and impedance changes by the modified current sources.