The invention discloses an in-pile flow distribution device of a reactor of a nuclear power station. The device is used for distributing flow of a reactor core coolant; the flow distribution device comprises a lower reactor core support plate, a surrounding basket-shaped structure and vertical columns, wherein the surrounding basket-shaped structure is fixed below the lower reactor core support plate and comprises a porous surrounding basket and an eddy-current confinement plate positioned at the bottom of the porous surrounding basket; a plurality of flowing holes are respectively formed in the porous surrounding basket and the eddy-current confinement plate; the vertical plates are vertically arranged between the eddy-current confinement plate and the lower reactor core support plate. The in-pile flow distribution device of the reactor of the nuclear power station is relatively simple in structure, and by stirring and mixing the coolant through the eddy-current confinement plate and the vertical columns, eddy-current of a lower chamber is effectively inhibited, and the structure of the lower chamber is prevented from vortex shedding. The coolant is subjected to twice flow distribution through the surrounding basket-shaped structure and the lower reactor core support plate, so that the distribution effect is better, and the flow distribution uniformity in a reactor core fuel component is better.