A slidable wind instrument brace has an adjusting ring, a first abutting block and a second abutting block. The first abutting block and the second abutting block are respectively mounted on two ends of the adjusting ring. The adjusting ring is rotated to drive the first abutting block and the second abutting block to move close to or away from each other. Therefore, a position of the brace is changeable and a wind instrument with the brace can produce different timbres.