The present invention provides a method for determining BSIMSOI4 Direct Current (DC) model parameters, where a plurality of Metal Oxide Semiconductor Field Effect Transistor (MOSFET) devices of a body leading-out structure and of different sizes, and a plurality of MOSFET devices of a floating structure and of different sizes are provided; Id-Vg-Vp, Id/Ip-Vd-Vg, Ig-Vg-Vd, Ig-Vp, Ip-Vg-vd, Is/Id-Vp, and Id/Ip-Vp-Vd properties of all the MOSFET devices of a body leading-out structure, and Id-Vg-Vp, Id-Vd-Vg, and Ig-Vg-Vd properties of all the MOSFET devices of a floating structure are measured; electrical property curves without a self-heating effect of each MOSFET device of a body leading-out structure and each MOSFET device of a floating structure are obtained; and then DC parameters of a BSIMSOI4 model are successively extracted according to specific steps. In the present invention, proper test curves are successively selected according to model equations, and various kinds of parameters are successively determined, thereby accurately and effectively extracting the DC parameters of the BSIMSOI4 model.