This article gives a modeling method based on the Gummel-Poon model for the Super-Gain BJT developed in the GREMAN laboratory. First of all, the extraction principle, mathematical calculating method, and final extraction results of each model parameter will be presented. Secondly, the Gummel and Voltage-Current output curves for a single Super-Gain BJT, which are carried on in Pspice with the extracted parameters in the first part, will be drawn and be compared with experimentation results. At last, a new 600V AC switch that is composed of two single Super-Gain BJTs connected in antiseries is simulated. To explain and reduce the error between the simulated results and experimental ones in hi-level injection, a new model with a dynamic resistance based on that of Gummel-Poon is proposed and validated. Consequently, all of simulations have an error less than 10%, proving the good precision of the models as well as the characteristics of the new AC power switch.