The present application discloses a method for manufacturing a gate-all-around field effect transistor, comprising the steps of: forming a suspended fin in a semiconductor substrate; forming a gate stack around the fin; and forming source/drain regions in the fin on both sides of the gate stack, wherein an isolation dielectric layer is formed in a portion of the semiconductor substrate which is adjacent to bottom of both the fin and the gate stack. The present invention relates to a method for manufacturing a gate-all-around device on a bulk silicon substrate, which suppress a self-heating effect and a floating-body effect of the SOI substrate, and lower a manufacture cost. The inventive method is a conventional top-down process with respect to a reference plane, which can be implemented as a simple manufacture process, and is easy to be integrated into and compatible with a planar CMOS process. The inventive method suppresses a short channel effect and promotes miniaturization of MOSFETs.