The invention relates to a folding chair, which comprises a coplanar rigid hinging device, a parallel planar rigid hinging device, a crossed planar rigid hinging device, various horizontal hinging pipes, various oblique crossing pipes, an upper hinging support, a lower hinging support or a lower hinging sliding sleeve support, leg pipes, armrest pipes, a back
pipe, elastic ropes, a rotating rod, atwo-dimensional
rotating hinge and the like, and each type of plane rigid hinging device is correspondingly arranged on each type of horizontal hinging
pipe. When the folding chair is unfolded, the horizontal hinge pipes can fall into or be wedged into the corresponding coplanar rigid hinge devices, the parallel planar rigid hinge devices and the crossed planar rigid hinge devices to be oppositely clamped into the groove-shaped openings, so that the horizontal hinge pipes are firmly clamped, complete rigid hinge of two or more groups of composite crossed folding chairs is realized, and the armrest pipes and the back
pipe are connected through the elastic ropes and can be easily and conveniently inserted and pulled out, so that the packaging volume of the folding chair is reduced, the logistics cost is reduced, and the folding chair is more convenient to carry.