[en] A group decoupled direct fitting method is developed for multi-group pin power reconstruction, which avoids either the complication of constructing 2D analytic multi-group flux solution or any group coupled iteration. In addition to nodal volume and surface average fluxes and corner fluxes, transversely integrated 1D nodal solution flux profiles are also used. For each energy group, a two-dimensional expansion in nine polynomials and eight hyperbolic functions is used to perform a constrained least squared fit to the 1D intra-nodal flux solution profiles. The constraints are on the conservation of nodal volume and surface average fluxes and corner fluxes. The corner fluxes are determined thru the condition of corner currents conservation. An optional slowing down source improvement method is also developed to further enhance the solution if needed. Two test examples are shown with very good results. One problem is a four-group BWR mini-core with all control blades inserted and the other problem is the OECD seven-group MOX benchmark, C5G7. (authors)