For the advanced high speed digital circuits with faster edge rate, smaller packaged size, and higher layout density, crosstalk becomes one of the serious problems for good signal integrity (SI) in the circuits. Accurate extraction of the equivalent model of the general three conductors transmission lines structure can help us understand the behavior of the crosstalk phenomenon. Based on combining the Layer Peeling Technique (LPT) and Finite-Difference Time-Domain (FDTD) numerical approach, both the impedance profile and the equivalent lumped model of the three-conductors transmission lines are theoretically obtained. The equivalent model can easily incorporate into SPICE program. The transient behavior of the these extracted model is compared with the experienced results measured by Time-domain Reflectometry (TDR). The agreement is good.