Using first principles calculations, we have investigated the pressure effects on the electronic and optical properties of Tungsten Disulfide. The results show that the lattice out plane is more sensitive to the pressure than that in plane. In addition, the conduction band maximum drops down and the valence band minimum shifts up with respect to the Fermi level, respectively. Semiconductor to metal transition occurs at a critical pressure (similar to 36 GPa). Moreover, the dielectric function also has an obviously red shift, and the optical absorption can be improved accordingly. Our study supplies a route to optimize the performance of WS2 devices. (C) 2016 Elsevier B.V. All rights reserved.