A collapsible peripheral frame includes first and second outer lateral bar units, and first and second longitudinal bar assemblies. Each of first and second longitudinal bar assemblies comprises first, second and third longitudinal bar units rotatably connected with each other at their adjacent ends. The first outer lateral bar unit has a first end connected with an end of the first longitudinal bar unit in the first longitudinal bar assembly and a second end rotatably connected with an end of the third longitudinal bar unit in the second longitudinal bar assembly. The second outer lateral bar unit has a first end rotatably connected with an end of the third longitudinal bar unit in the first longitudinal bar assembly and a second end connected with an end of the first longitudinal bar unit in the second longitudinal bar assembly.