Abstract: A locking device includes a base, a hook pivoted to the base to move between an engaging position and a releasing position, a sliding member slidably disposed at the base and locked to the base to maintain the hook at the releasing position, a knob pivoted to the base, and an actuating member slidably disposed at the base. The sliding member slides relative to the base to be disengaged from the hook or to drive the hook to be transported to the releasing position. The knob rotates relative to the base and blocks the sliding member from sliding or allows the sliding member to slide relative to the base. The actuating member receives a force to slide relative to the base and drives the sliding member to be disengaged from the base and moved and disengaged from the hook to allow the hook to be transported to the engaging position.