In this paper, the characteristics of a class of transmission lines which support spoof surface plasmon polaritons are investigated both numerically and experimentally. In order to provide the characteristic impedance of spoof surface plasmon polaritons for PCB designers, the equivalent circuit parameters of the microstrip line periodically structured on subwavelength scale are extracted with the numerical method. It is found that the equivalent circuit parameters significantly vary with frequency when the subwavelength periodic structure is introduced into the edge of the conventional microstrip line. The results of time-domain measurements show that spoof surface plasmon polaritons have remarkable advantage over conventional microstrip lines and can be directly used in actual high-speed circuits, which is helpful for eliminating the doubts whether the metamaterials can be directly used in actual circuits.