The present invention discloses a semiconductor device, comprising substrates, a plurality of gate stack structures on the substrate, a plurality of gate spacer structures on both sides of each gate stack structure, a plurality of source and drain regions in the substrate on both sides of each gate spacer structure, the plurality of gate spacer structures comprising a plurality of first gate stack structures and a plurality of second gate stack structures, wherein each of the first gate stack structures comprises a first gate insulating layer, a first work function metal layer, a second work function metal diffusion blocking layer, and a gate filling layer; Each of the second gate stack structures comprises a second gate insulating layer, a first work function metal layer, a second work function metal layer, and a gate filling layer, characterized in that the first work function metal layer has a first stress, and the gate filling layer has a second stress. Two metal gate layers of different types and/or intensity of stress are formed, respectively, thus different stresses are applied to the channel regions of different MOSFETs effectively and accurately, the device carrier mobility is enhanced simply and efficiently, and the device performance is also enhanced.