A new, improved grid spacer for a nuclear fuel assembly is provided, comprising several straps which intersect each other alternatively to form a plurality of grid cells and fuel rods reside in some of the grid cells; the grid spacer further comprises mixing elements set at the corner of the grid cells in which the fuel rods have resided; wherein the mixing element comprises a mixing vane stretching towards the direction of the fuel rod and a flow funnel set on the bended edge of the mixing vane continuously and extending towards adjacent grid cells; the mixing vane and the flow funnel set across two sides of two adjacent grid cells respectively, and the flow funnel introduces the coolant in the grid cell at its side to the mixing vane, then the mixing vane introduces the coolant to the grid cell at its own side.