The invention relates to a method for molding U-shaped tube, which is characterized in that: when producing the U-shaped tube, moving along the guide grooves at two sides of its slicing surface A-A via chain and the annular ring connected to the chain, to connect the section core annular ring at the surface A-A; when the U-shaped tube is molded, extracting out the core, the chain will draw out the annular ring along the guide groove; then taking the tube outside the mould, to repeat aforementioned steps. The invention also provides a relative section core. And the section core can automatically demould, and the produced tube has no dead corner, to improve the producing efficiency and reduce the cost. |