Abstract: To investigate the superconductivity induced by 5d element doping in and physical pressure on Fe-based superconductor, the crystal structure of SmFeAsO was calculated, and the effects of pressure and Ir doping at Fe site on the lattices, electronic and magnetic properties of SmFeAsO were analyzed using SGGA+U(the spin generalized gradient approximation plus Hubbard model) method. The results show that the coulomb interaction between Fe-3d electrons is about 4 eV. The decreased magnetism indicates that the antiferromagnetic spin density wave (SDW) of the Fe-based compound SmOFeAs will be suppressed by physical pressure and chemical doping, which is in agreement with experimental results. Electron doping with Ir cause the SmFe1-xIrxAsO system to change from an antiferromagnetic SDW state into a nonmagnetic one, with superconductivity coexisting with antiferromagnetism and occurring in the vicinity of a magnetic quantum critical point.