Foldable height-increasing stool with backrest

A foldable height-increasing stool with a backrest, comprising:

• a base;
• a lifting assembly mounted above the base and including a plurality of load-bearing rings nested and assembled sequentially from outside to inside, a lifting locking structure being provided between the adjacent load-bearing rings;
• a stool panel mounted above the lifting assembly;
• and
• a backrest rotatably mounted at a rear end of the stool panel and having a stowed state abutting against an upper portion of the stool panel, and a use state of pivoting upward away from the stool panel, in the use state, a positioning structure that cooperates to fix a position of the backrest being provided between the backrest and the stool panel, wherein
• the lifting locking structure has a locking position and an unlocking position, and is switched therebetween through same-direction and circumferential rotation of all the load-bearing rings, in the use state, the adjacent load-bearing rings are mutually pulled to the farthest end, so that the lifting locking structure is at the locking position and fixes relative positions of all the load-bearing rings;
• and in the stowed state, the lifting locking structure is switched to the unlocking position, all the load-bearing rings are lowered to a height of the lowermost load-bearing ring, and the stool panel and the base cooperate to cover the lifting assembly.