A polygonal one-piece foldable water basin, comprising a water basin body, wherein the water basin body is connected with at least one water outlet, a supporting frame is provided at an inner side of the water outlet close to an edge thereof, a tarpaulin is provided in an outer side of the water basin body; the tarpaulin comprises a mesh and a base cloth; the base cloth is made of high strength terylene and/or chinlon, coated with PVC paste at both sides thereof and dried; the mesh is a high strength square mesh, and the mesh is connected and welded to the base cloth by high temperature processes to form the tarpaulin; by providing the tarpaulin at an outer portion of the water basin the water basin is reinforced, the tarpaulin is provided with the high strength square mesh, the mesh is inelastic and enclosed in the tarpaulin.