wiring topology designed software provides a flow network to simulate the wiring topology the hardware in the method for designing wiring topology is described as below the computer has an input unit an operating unit a storage unit and an output unit the input unit is a keyboard or a handwriting input device the operation unit is a central processing unit cpu the storage unit is a hardware electrically connected to the input unit the operating unit and the output unit the wiring topology designed software is installed in the hardware the output unit is a display or a printer refer to fig1 for a chart showing the method for designing wiring topology the steps of the method are described as below step 100 input the positions and the source currents of the sources x si y si f si the positions and the sink currents of the sinks x tj y tj f tj a minimal wiring length w min a maximal wiring length w max and a maximum tolerable current density j max by an user of the wiring topology designed software via the input unit wherein the wiring topology has a plurality of sources a plurality of sinks and a plurality of wires each of the wires is straightly connected between one of the sources and one of the sinks and an effective current flows from one of the sources into one of the sinks through each of the wires step 101 calculate the length of all the wires to choose the minimum among all the wires as a feasible wire which has a minimal length of all the wires via the operating unit step 102 decide a capacity of the feasible wire and an effective current of each feasible.