The invention discloses an equivalent electrical model of a silicon-on-insulator (SOI) field effect transistor of a body leading-out structure and a modeling method thereof. The equivalent electrical model consists of an internal field effect transistor and an external field effect transistor connected in parallel, wherein the SOI field effect transistor of the body leading-out structure is divided into a body leading-out part and a main body part; the internal field effect transistor represents a parasitic transistor of the body leading-out part; and the external field effect transistor represents a normal transistor of the main body part. The equivalent electrical model provided by the invention completely comprises all parts of the physical structure of a silicon-on-insulator metal oxide semiconductor field effect transistor (SOI MOSFET) device of the body leading-out structure, namely influence of the body leading-out part and the main body part on the electrical property of the device; and the fitting effect of the model on the electrical property of the device is improved.