The magnetic properties of CeRhIn5 are studied by first-principles calculation. Spin-orbit coupling is considered as well as different corrections including local density approximation plus on-site Coulomb interaction U (U = 1,1.5, 3 eV) and orbital polarization. The results show the existence of only moderate correlation in CeRhIn5 and Ce-4f electrons are on the border of localization and itinerancy. The effect of pressure by changing the volume of the unit cell is also studied.