In this work, effects of shape and size of the pores on the mechanical properties of nanoporous graphene (NPG) membranes are studied. Molecular dynamics simulations were performed to study the mechanical and structural responses under uniaxial traction. The results of the stress-strain curves of NPG membranes show an elastic linear behavior for small strain (<0.03) independent of the chiral direction. The chiral anisotropy (armchair and zigzag direction) is notable as deformation increases to the point of fracture. The NPG membranes with hexagonal and rectangular pores present a higher fracture stress (65 GPa and 81 GPa, respectively). Furthermore, Young’s elastic modulus decreases as pore size increases (porosity). This study is expected to provide practical application as high performance membrane filters.