All the possible three-family {mathcal N}=1 supersymmetric Pati–Salam models constructed with intersecting D6-branes from Type IIA orientifolds on T^6/(mathbb {Z}_2times mathbb {Z}_2) are recently presented in arXiv:2112.09632. Taking models with largest wrapping number 5 and approximate gauge coupling unification at GUT scale as examples, we show string scale gauge coupling unification can be realized through two-loop renormalization group equation running by introducing seven pairs of vector-like particles from {mathcal N}=2 sector. The number of these introduced vector-like particles are fully determined by the brane intersection numbers while there are two D6-brane parallel to each other along one two-torus. We expect this will solve the gauge coupling unification problem in the generic intersecting brane worlds by introducing vector-like particles that naturally included in the {mathcal N}=2 sector.