Threshold voltage of SiC Schottky barrier source/drain MOSFET (SBSD MOSFETs) is different from the threshold voltage of traditional MOSFETs. Based on a comprehensive analysis of the operational mechanism，the threshold voltage of SBSD MOSFET is extracted and analyzed with 2-D simulator ISE. The threshold voltage of the device is defined as the gate voltage at which carriers from the source contact enter the channel by field emission while the channel is strongly inverted.