Abstract: Pseudo-resonant-nuclide subgroup method (PRNSM) is capable to treat spatially self-shielding effect in fuel rod. However, it requires the number densities of resonance nuclides to be constant throughout the whole fuel region, so the spatial distributions of resonance nuclides’ densities caused by rim effect cannot be taken into account. To solve this problem, a new method was proposed on the base of improved pseudo-resonant-isotope-theory. Numerical results show that this method solves the limit of PRNSM on rim effect and has higher accuracy than Bondarenko iteration method and resonance interference factor method.