The invention relates to a fuel assembly for a nuclear reactor. The fuel assembly comprises a filtering device, a grillage which is longitudinally arranged on the filtering device and fuel rods which are longitudinally arranged in the grillage, wherein the filtering device comprises a plurality of unit plates which are arrayed in turn, and any two adjacent unit plates are spliced with each other at joints so as to form a plurality of penetrated longitudinal fluid through holes; the grillage comprises a plurality of first strips and a plurality of second strips, and the first strips and the second strips are matched with each other so as to form a plurality of grid units; the fuel rods are correspondingly located in the grid units; and the projection scope of at least one grid unit only contains one joint. The projection scope of the grid units only contains one joint of the filtering device in the manner of adjusting the position of the grid units, so that the first strips and the second strips of the grid units can be utilized as stopping components for cutting a water outlet of the filtering device, and then the filtering capacity is further promoted.