Abstract: A balance assembly adapted for an exercise auxiliary system includes a base, a supporting seat pivotally engaged with the base, multiple springs sandwiched between the supporting seat and the base to support the base and a fixed seat slidably connected to the supporting seat via wheels mounted on opposite sides of the supporting seat. The base has two phases, a pre-movement phase and an in-movement phase. In the pre-movement phase, the base is still resulted from supporting force from the springs and in the in-movement phase, the base rocks.