A protective case for a mobile phone and a tablet computer, comprising: a main body and a rotatable bottom support located at one end of the main body; a surface support configured to match with the bottom support disposed on a second end of the main body, and a supporting plate disposed on the surface support; wherein the bottom support comprises: - a limiting surface configured to match with the surface support, - elastic positioning parts disposed on the bottom support, - positioning points, wherein the bottom support and the surface support are positioned in a connecting process by the positioning points, - and a plurality of limiting columns to position the surface support; wherein the surface support matches with the bottom support in such a way that form into a whole with the bottom support; the plurality of the limiting columns are uniformly disposed on an upper end of the limiting surface; and wherein the elastic positioning parts are made of plastic so a production and assembly error is solved by utilizing free elasticity of the plastic; the positioning points are uniformly disposed on the bottom support outside of the elastic positioning parts, wherein the supporting plate is hinged with the surface support for adjusting the supporting angles arbitrarily, a hinged position of the supporting plate and the surface support is connected by a telescopic mechanism for adjusting a distance between the supporting plate and the surface support. a main body and a rotatable bottom support located at one end of the main body; a surface support configured to match with the bottom support disposed on a second end of the main body, and a supporting plate disposed on the surface support; wherein the bottom support comprises: - a limiting surface configured to match with the surface support, - elastic positioning parts disposed on the bottom support, - positioning points, wherein the bottom support and the surface support are positioned in a connecting process by the positioning points, - and a plurality of limiting columns to position the surface support; - a limiting surface configured to match with the surface support, - elastic positioning parts disposed on the bottom support, - positioning points, wherein the bottom support and the surface support are positioned in a connecting process by the positioning points, - and a plurality of limiting columns to position the surface support; wherein the surface support matches with the bottom support in such a way that form into a whole with the bottom support; the plurality of the limiting columns are uniformly disposed on an upper end of the limiting surface; and wherein the elastic positioning parts are made of plastic so a production and assembly error is solved by utilizing free elasticity of the plastic; the positioning points are uniformly disposed on the bottom support outside of the elastic positioning parts, wherein the supporting plate is hinged with the surface support for adjusting the supporting angles arbitrarily, a hinged position of the supporting plate and the surface support is connected by a telescopic mechanism for adjusting a distance between the supporting plate and the surface support.