A ground gauge changing apparatus for a gauge-changeable wheelset. The ground gauge changing apparatus comprises a pair of support rails (10) disposed in parallel, and a pair of first guide rails (20), a pair of gauge-changeable guide rails (30) and a pair of second guide rails (40) that are sequentially disposed on the inner sides of the pair of support rails (10). Unlocking segments (50) are disposed between the first guide rails (20) and the gauge-changeable guide rails (30), and unlocking emergency braking segments (51) are disposed between the unlocking segments (50) and the gauge-changeable guide rails (30). Locking segments (60) are disposed between the gauge-changeable guide rails (30) and the second guide rails (40), and locking emergency braking segments (61) are disposed between the locking segments (60) and the second guide rails (40). The ground gauge changing apparatus can eliminate the potential safety hazards in an existing ground gauge changing apparatus and avoid the occurrence of heavy losses.