Connecting device for child carrier and child carrier and child crib

A child crib, comprising:

• upright posts;
• top corner members fixedly connected to the upright posts;
• and
• handrail assemblies connected between the top corner members, the handrail assemblies comprising handrail tubes and handrail seats, the handrail seats being located between the adjacent top corner members, inner ends of the handrail tubes being pivotally connected to the handrail seats, and outer ends of the handrail tubes being pivotally connected to the adjacent top corner members, respectively;
• side wall seat cloths including side fence parts surrounding the upright posts;
• and
• an upper sheath part covering the top corner members and the handrail assemblies and comprising an inner side portion and an outer side portion connected to each other, a lower edge of the inner side portion being fixedly connected to the side fence part, a lower edge of the outer side portion being connected to the side fence part through two connecting structures and forming a first opening with the side fence part, the two connecting structures being located on both sides of the handrail seat in an extension direction of the handrail assembly,
• wherein the child crib comprises an unfolded state and a folded state and is capable of being converted between the unfolded state and the folded state, and in a process of converting the child crib from the unfolded state to the folded state, the first opening allows the handrail seat to move downward relative to the upper sheath part.