The invention relates to manufacturing of special-shaped tundish working linear loose tooling. One end of the top view of the loose tooling is in the shape of a 'fish mouth'. In order to ensure the manufacturing precision of the special-shaped loose tooling and reduce manufacturing difficulty, the invention begins from the design, the loose tooling is divided into five regions at first, and the 'fish-mouth'-shaped region is independently welded and manufactured; and the support of the inside of the loose tooling is designed into an integral 'double-stacked-square'-shaped steel plate support, and welding operation of a mold shell is carried out surrounding the integral support. In order to ensure uniformity of the temperature and pressure in the loose tooling, an ignition box is added in each baking region, a steady hot flow from bottom to top is formed by the ignition boxes and smoke discharging holes, and thus, the temperatures of all positions in the region are always content; and secondarily, by introduction of the 'double-stacked-square'-shaped steel plate support with a hole in the middle, the five regions communicate with one another, and thus, the temperature and pressure inthe loose tooling are constant.