A connecting device, comprising: a first connecting member, comprising a first fixed part, a first movable part provided in a manner of moving in a first direction and a first elastic part positioned between the first fixed part and the first movable part, the first fixed part being provided with a first component connecting part and the first movable part being provided with a mounting through hole which is through in a second direction perpendicular to the first direction; and a second connecting member matched with the first connecting member, provided with a second component connecting part and an accommodation groove for accommodating a hole wall of the mounting through hole, the second connecting member having an inward extension state of extending into the mounting through hole and an outward shifting state of shifting out of the mounting through hole, the first movable part having a connection state of causing the hole wall of the mounting through hole to extend into the accommodation groove and a separation state of causing the hole wall of the mounting through hole to extend out of the accommodation groove and the first movable part being in the connection state under an action of the first elastic part; the second connecting member comprises a second fixed part and a second movable part provided on the second fixed part in the manner of moving in the second direction, the second component connecting part is formed on the second fixed part, the accommodation groove is formed in the second movable part, and the second movable part has the inward extension state and the outward shifting state; the accommodation groove is an annular groove, the second fixed part is provided with a threaded hole which is through in the second direction, the second movable part comprises a hanger rod, the accommodation groove is formed in the hanger rod, and the hanger rod is provided with an external threaded section matched with the threaded hole. a first connecting member, comprising a first fixed part, a first movable part provided in a manner of moving in a first direction and a first elastic part positioned between the first fixed part and the first movable part, the first fixed part being provided with a first component connecting part and the first movable part being provided with a mounting through hole which is through in a second direction perpendicular to the first direction; and a second connecting member matched with the first connecting member, provided with a second component connecting part and an accommodation groove for accommodating a hole wall of the mounting through hole, the second connecting member having an inward extension state of extending into the mounting through hole and an outward shifting state of shifting out of the mounting through hole, the first movable part having a connection state of causing the hole wall of the mounting through hole to extend into the accommodation groove and a separation state of causing the hole wall of the mounting through hole to extend out of the accommodation groove and the first movable part being in the connection state under an action of the first elastic part; the second connecting member comprises a second fixed part and a second movable part provided on the second fixed part in the manner of moving in the second direction, the second component connecting part is formed on the second fixed part, the accommodation groove is formed in the second movable part, and the second movable part has the inward extension state and the outward shifting state; the accommodation groove is an annular groove, the second fixed part is provided with a threaded hole which is through in the second direction, the second movable part comprises a hanger rod, the accommodation groove is formed in the hanger rod, and the hanger rod is provided with an external threaded section matched with the threaded hole.