Type IV thumb dysplasia, also known as floating thumb, is clinically characterized by a flimsy thumb root with only a flaccid dermal canal attached and a lack of metacarpal bone or only the remains of metacarpal bone. The affected hand completely loses the function of the thumb and is unable to flex, extend, pinch, or pinch, and the floating thumb can only swing with the hand. The thumb cannot be used and the role of the tiger’s mouth is lost, so the hand function is greatly weakened and can only pinch and grip objects, which brings great inconvenience to life. Many children with floating thumb develop the habit of pinching objects with their index and middle fingers because of the lack of timely surgical intervention, which leads to deformity of the index and middle fingers in the long run. Therefore, for floating thumb, we emphasize the importance of reconstructing the function of the thumb, firstly, and secondly, as early as possible. The first treatment plan for drift thumb was mainly to show finger thumbing, where the drift thumb was directly removed and the index finger was transferred to the position of the thumb and used as a thumb. Although this method had the function of the thumb, the child had only four fingers from then on, which many parents could not accept and felt it was a disability. Later, metatarsal reconstruction was used to take part of the metatarsal bone from the foot to rebuild the first metacarpal. After the operation, the child could not go down to the ground for three months, and could only lie or sit, which was more troublesome for parents to take care of, and there was a certain chance of bone resorption and necrosis. This solution can save the five fingers, but it will cause great damage to the foot, which will be permanently damaged and cannot run or jump strenuously from now on. Now we are using the hemi-metacarpal bone graft reconstruction (SMRT floating bunion reconstruction) to treat floating bunions, where a portion of the bone is taken from the second metacarpal of the affected hand to reconstruct the first metacarpal. The most important thing is that the surgery is advanced to about 6 months to one year of age, so that the child can establish the function of the thumb earlier.