A model-building method and a model-building system for executing the method are disclosed. The method includes the following steps: reading a first netlist; extracting a netlist between an input and an initial-stage clock multi-vibrator and extracting a netlist between a final-stage clock multi-vibrator and an output from the first netlist; extracting a netlist between the input and the output from the first netlist; extracting a netlist between a first clock multi-vibrator and a second clock multi-vibrator from the first netlist; extracting netlists between the first clock input and the initial-stage clock multi-vibrator and the first clock multi-vibrator from the first netlist; extracting netlists between the second clock input and the final-stage clock multi-vibrator and the second clock multi-vibrator from the first netlist; and generating a second netlist based on extracted netlists.