The invention discloses a clamp used for a SiC MESFET (Metal Semiconductor Field Effect Transistor) direct current test, belonging to the field of field effect transistor tests. The clamp comprises a PCB (Printed Circuit Board) distributed with a filter circuit and a metal board carrying the PCB, wherein the metal board is provided with a groove for fixing a SiCMESFET device to be tested, the PCB is provided with a through hole corresponding to the groove, the filter circuit includes a grid filter circuit and a drain filter circuit, the output ends of the grid filter circuit and the grain filter circuit are respectively connected with a grid transmission wire and a drain transmission wire through offset lines, one ends of the grid transmission wire and the drain transmission wire are respectively provided with a contact respectively connected with a grid electrode and a drain electrode of the SiC MESFET device to be tested, and the other ends of the grid transmission wire and the drain transmission wire are respectively provided with a self-excitation prevention module. The clamp can eliminate self-excitation of the device by the self-excitation prevention modules, improve device test efficiency and accumulate valuable data for the representation of device characteristics.