Accurate simulation is an essential task in designing of integrated power systems to predict their electrical behavior. Thus, a very good description of their wiring circuits is required, and the availability of accurate models of power semiconductor devices and associated design parameters is crucial. This paper focuses on a novel extraction approach of design parameters for a 1-D finite-element-method model of the thyristor. These design parameters are also essential for physics-based analytical models. This paper presents an extraction procedure of the main design parameters of an ultrafast thyristor: the effective area of the device, the ambipolar lifetime, the doping concentration and width of the low-doped base region, and the doping concentration and width of the gate region. The extraction procedure of the thyristor design parameter is based on a comparative computation between simulation and experimental results, taking into account the physics of the component. Measurements are carried out on a sophisticated test circuit, which must be modeled with a sufficient accuracy. This paper details the parameter extraction procedure. Various electrothermal simulation results about the thyristor under test, using the extracted values of design parameters, show good agreement with experiment and confirm the validity of the presented extraction procedure.