Abstract: A ratchet wheel having a locking device, includes a housing, a ratchet wheel disposed pivotally in the housing in such a manner that one end of its axle couples with an external rotating object, a braking member having a shank provided at one end thereof with a wedge angle and at other end thereof with a pivot, and a lock. The pivot is coupled pivotally with the housing in such a way that it moves between a first position and a second position. When the braking member is at the first position, its wedge angle meshes with ratchet wheel. When the braking member is at the second position, its wedge angle disengages from the ratchet wheel. The lock has a lock core capable of moving between a locking position and an unlocking position. The locking position of the lock core corresponds to the first position of the braking member, while the unlocking position of the lock core corresponds to the second position of the braking member.