Abstract: Nodal method is widespread used in reactor core diffusion code, but as nodal method adopting coarse mesh in order to speedup calculation, so it causes cusping effect. Cusping effect would affect some reactor core diffusion relevant calculation result. In this paper, the partial inserted rod intro-node cross section in nodal method transverse integration equation was explicitly represented, i.e. node axial position dependent cross section step function was introduced. Numerical results indicate the method greatly improves the control rod differential worth deviation of cusping effect, in particular nearly completely eliminates the control rod relevant kinetic problem’s deviation of this effect.