The invention provides a child safety seat connecting mechanism. The child safety seat connecting mechanism comprises a connecting frame, a clamping piece and a driving piece. A locking cavity is formed in one end of the connecting frame, the clamping piece is provided with a hook part, when a connecting object is clamped into the locking cavity, the hook part of the clamping piece is screwed into the locking cavity to close an opening of the locking cavity, and the hook part of the clamping piece can be driven by the driving piece to be screwed out of the locking cavity to open the opening of the locking cavity. The child safety seat connecting mechanism is characterized in that a runway-shaped movable hole is formed in the clamping piece, a first pin shaft is arranged in the movable hole, the clamping piece can move relative to the first pin shaft through the size of the movable hole, and a first blocking part capable of abutting against the hook part is arranged at the end, provided with the locking cavity, of the connecting frame. When the connecting object clamped into the locking cavity is pulled outwards, the connecting object acts on the hook part, the clamping piece is driven to move till the hook part of the clamping piece abuts against the first blocking part, acting force generated when the driving piece limits the hook part from being not actively screwed out of the locking cavity is reduced, and then starting acting force needed when the driving piece drives the hook part to be screwed out of the locking cavity can be reduced.