With the rapid increases of signal frequency and reduction of feature sizes of high-speed electronic circuits in modern VLSI design, it is becoming more and more important to design and optimize power/ground networks fast and efficiently. A method for the design of the power/ground networks at the floor-planning stage is presented, which calculates the number of pads and straps and width of straps first, and then optimizes the power/ground networks considering the Macro's power consumption. Experimental results based on the digital television transmitter modulator design show that final IR drop is within the required range and the method is efficient and reliable.