This invention discloses a method for manufacturing field effect transistors with channels composed of silicon fins and silicon main bodies and the transistors, in which, the orientation of the fin is defferent from the silicon main body. The method includes the following steps: a, forming a hard mask pattern on a base plate including a Si film, b, etching the Si film to a preset thickness anisotropically using said pattern as the mask so as to form not only Si fins going to form channels and Si pattern with source/drain region but also form a Si main body connecting the fins to form channels, c, using the active mask to etch the Si film partly to isolate the source/drain region and the device and d, growing grid dielectric film on the Si channels and depositing grid material and grid mask on the structure to form a grid region.