The invention relates to a connection structure of an operating crank and a screw for a switch cabinet. The connection structure includes a screw and an operating crank, wherein the screw is connected with a length-adjustable connecting piece; the connecting piece includes a bolt and a connecting rod; the bolt includes a screw part and a head; the connecting rod is connected with the head; the diameter of the head is equal to the diameter of the screw; the screw part is fixedly connected with the screw; a through hole is formed in the operating crank; and a locking assembly is arranged on the connecting rod. The connection structure of an operating crank and a screw for a switch cabinet has the advantages that as the length-adjustable connecting piece is arranged on the screw and penetrates through the through hole, and as the locking assembly locks the operating crank on the connecting piece to increase the contact length and the contact area between the operating crank and the screw, loosening and shedding of the operating crank during the operation process can be prevented effectively and fixing of the operating crank and the screw is reliable so that the operation is convenient and the connection is reliable and the safety effect is good during the operation process; and as the connecting piece is formed by the bolt and the connecting rod and the connecting rod is fixedly connected with the head of the bolt and the screw part of the screw is fixedly connected with the screw, the length of the connecting piece can be adjusted in real time so that the practicality is high.