The structural and electronic properties of crystalline pentacene has been investigated within the framework of density functional theory including van der Waals interactions. The computed lattice parameters have good agreement with experimental data. We studied on the structural and electronic properties of the pentacene under the hydrostatic pressure of 0-10 GPa. The isothermal equations of state calculated from the results show good agreement with experiment in the pressure intervals studied. Using the Murnaghan equation of state it has been established that compression bulk modulus is B0=11.42 GPa and it has good agreement with the experimental value. We have also calculated the quasiparticle band structure of pentacene with the G0W0 approximation.