A foldable chair, comprising: a foldable chair frame and a chair seat made of a flexible material; the chair frame comprising an X-shaped left support frame , an X-shaped right support frame and a connecting crossbar with two ends connecting the left support frame and the right support frame , the chair seat having a top edge, a bottom edge, and a backside, the chair seat connecting to the chair frame through a plurality of connecting pieces disposed on the top and bottom edges of the backside of the chair seat ; each of the left support frame and the right support frame has a detachable pole extending from top to bottom of the chair frame , and the connecting crossbar has two first through holes for the poles to pass through, each of the left support frame and the right support frame has a support tube extending from the bottom edge of the chair seat to the bottom of the chair frame , and correspondingly, the connecting crossbar has two second through holes for the support tubes to pass through, and each of the detachable pole and its corresponding support tube form the X-shaped left support frame or the X-shaped right support frame ; wherein the second through holes and the first through holes are distributed inclined in X shape; wherein each of the pole comprises an upper pole body and a lower pole body detachably connected to each other; a hand grip portion is disposed at an upper end of the upper pole body , a leg portion is connected to a lower end of the lower pole body ; the upper pole body and the lower pole body are detachably connected through a locking pipe , the lower pole body is inserted into the leg portion and then fixed by a locking sleeve , and the outer end of the connecting crossbar is sleeved on the lower pole body and disposed above the locking sleeve . a foldable chair frame and a chair seat made of a flexible material; the chair frame comprising an X-shaped left support frame , an X-shaped right support frame and a connecting crossbar with two ends connecting the left support frame and the right support frame , the chair seat having a top edge, a bottom edge, and a backside, the chair seat connecting to the chair frame through a plurality of connecting pieces disposed on the top and bottom edges of the backside of the chair seat ; each of the left support frame and the right support frame has a detachable pole extending from top to bottom of the chair frame , and the connecting crossbar has two first through holes for the poles to pass through, each of the left support frame and the right support frame has a support tube extending from the bottom edge of the chair seat to the bottom of the chair frame , and correspondingly, the connecting crossbar has two second through holes for the support tubes to pass through, and each of the detachable pole and its corresponding support tube form the X-shaped left support frame or the X-shaped right support frame ; wherein the second through holes and the first through holes are distributed inclined in X shape; wherein each of the pole comprises an upper pole body and a lower pole body detachably connected to each other; a hand grip portion is disposed at an upper end of the upper pole body , a leg portion is connected to a lower end of the lower pole body ; the upper pole body and the lower pole body are detachably connected through a locking pipe , the lower pole body is inserted into the leg portion and then fixed by a locking sleeve , and the outer end of the connecting crossbar is sleeved on the lower pole body and disposed above the locking sleeve . <EOS>