As devices are scaling down aggressively, three-dimensional field-effect transistors (FETs) becomes one of essential factors to obtain high gate controllability in order to reduce leakage current. However, insulators surrounding channel for above the reason block heat emission so that the lattice temperature can increase to the critical levels for devices. This phenomenon, called Self Heating Effect (SHE), can deteriorate device performance significantly. From this point of view, overall study on SHE in 5 nm node Nanowire FET (NWFET) was implemented by simulation. Through analysis on on-current (I _on), thermal resistance (R _th), transient characteristics, the DC and AC characteristics were investigated.