Abstract: Single-curvature polyhedron hydrobulging technology is a method to build large spherical vessels without using dies and presses. With the method single-curvature cylindrical shell plates formed by common rolling machines are assembled and welded into an enclosed singlecurvature polyhedron, which are then hydrobulged into a spherical vessel. This paper stubie wallthickness distribution of a single-curvature polyhedron in the hydrobulging Process. The result shows that wall thickness distribution is not even. The thinning rate of the detecting point near a fillet welded joint is smaller than that of the detecting point far from the fillet welded joint, even negative. In a polar zone, the maximum rate is reached at the cotal point. In a singlecurvature cylindrical Shell plate, the maximum thinning rate happens at the intersection point of the meridian symmetrical line and latitudinal latitudinal line.