Cooling partitions for the U-valve relates to the solid material returning technology. The cooling partitions include an intermediate partition (4) located vertically between a downcomer (1) and a riser (2) of the U-valve, and a material returning partition (5) located vertically between the riser (2) and a return chute (3). The intermediate partition (4) and the material returning partition (5) comprise the cooling tube bundles and refractory covered at the outer surface of the cooling tubes. At least one end of the cooling tube bundles extends out of the casing of the loop seal and is connected with headers at the outside of the casing of the loop seal. There is cooling medium in the cooling tubes.