The invention provides a low-pressure-drop foreign matter prevention type lower pipe seat of a fuel assembly. The lower pipe seat comprises a supporting framework and a lower pipe seat grating fixed above the supporting framework, wherein the lower pipe seat grating comprises two layers of plates, the plate on one layer is a macroporous plate, and the plate on the other layer is a grid plate arranged above or below the macroporous plate; the grid plate is of a netty grid structure composed of vertical slices; the macroporous plate is of a flat plate structure matched with the grid plate in size, and a plurality of columns and rows of drain holes are uniformly formed in the macroporous plate; and each large circular drain hole is divided by grids of the grid plate into a plurality of parts on the overlooking projection, and each large circular drain hole is formed to avoid the projection position of a fuel bar. According to the lower pipe seat of the fuel assembly, provided by the invention, has the function of uniform flow rate distribution and can realize the balance of the strength, pressure drop and a foreign matter prevention function of the lower pipe seat as the macroporous plate is matched with the grid plate. The grid plate structure ensures the sufficient foreign matter filtering capability after the aperture is increased.