To press-pack devices, higher packaging resistance results in higher conduction losses. In this paper, compositions of the packaging resistance are studied for a press-pack SiC MOSFET. Firstly, an estimation method of body resistance of conducting layers in the press-pack SiC MOSFET with ANSYS Q3D is investigated, which is verified by the experiment. Since the Q3D resistance estimation method is unable to obtain contact resistances between different layers in the press-pack, the contact resistance estimation method is proposed. Finally, all resistances in the press-pack are obtained. It is concluded that the contact resistance is critical to the static loss of the press-pack. It is useful to the press-pack structure improvement in the future.