The installation is designed for loading a nuclear fuel assembly that comprises a skeleton structure defining parallel locations for receiving fuel rods distributed in sheets. The installation comprises a horizontal bench (22) for receiving a skeleton structure, a magazine (16) for receiving rods for loading in a disposition that corresponds to that of the rods in the assembly, and a pulling bench (26) having a block of pulling or pushing elements enabling a plurality of rods to be slid simultaneously from the magazine into the skeleton structure. The bench makes it possible for a set of clamps from a plurality of sets each corresponding to a particular type of assembly to be fixed removably thereto by quick coupling and uncoupling means closed by actuators. The pulling bench (26) receives one out of a plurality of pulling element selector blocks, each block having a disposition of active pulling elements corresponding to a particular distribution of rods.