Signal attenuation in transmission lines is a major issue for reliable transmission in high frequency circuit design. Electrical parameters, including permittivity, loss tangent and surface roughness loss, have great effects in high frequency. Moreover, the electrical parameters are frequency-dependent in high frequency. Therefore, it is critical to characterize the printed circuit board (PCB) materials. There are many techniques for material characterization based on PCB. Some of the methods are time-consuming, and some ignore the effects of the surface roughness. The goal of this thesis is to achieve an accurate and time-saving method for PCB electrical characterization. This thesis demonstrates an effective simulation fitting method for electrical characterization. Cavity resonators are used for characterization due to their low radiation properties. A methodology is presented to measure surface roughness from cross sections, and compared with the values extracted from resonator measurements. Several materials and copper foil treatments, including low-profile and electrodeposited, are analyzed in this thesis. Also, feature selective validation is used to quantify the fitting degree.