Child safety seat

A child safety seat, including: a seat housing; a headrest arranged on the seat housing in a height-adjustable manner; a top tether extending from the top of the seat housing for connection with an anchor point of a vehicle; a safety belt attached to the seat housing; and a locking apparatus arranged on the seat housing. The locking apparatus includes a locking member and an elastic member. The locking member is switchable between a lock position for locking one of the headrest and the safety belt and an unlock position for unlocking the one of the headrest and the safety belt, and the elastic member acts on the locking member to keep the locking member at the lock position. The top tether is configured to act on the locking member when tensioned, so that the locking member overcomes force of the elastic member to switch from the lock position to the unlock position.