The invention belongs to the field of underwater connectors and particularly provides a misplug-preventing watertight connector used for transmitting electrical signals in the underwater operation process. The watertight connector is installed on underwater equipment. A socket is provided with a navy copper case, jacks and guide holes, wherein the jacks and the guide holes are formed in a first rubber vulcanization seal body. One ends of the jacks are connected with wires, the other ends of the jacks are provided with independent inner cavities, and annular protrusions are arranged in the inner cavities. A second rubber vulcanization seal body of a plug is provided with pins and guide pins. The bottom of each pin is provided with an independent rubber insulation bar. One ends of the pins are connected with wires in cables, and the other ends of the pins are inserted into the jacks. The rubber insulation bars are inserted into the inner cavities and connected with the annular protrusions in a sealing and abutting mode. The socket and the corresponding plug can be plugged under the damp environment, and therefore the watertight connector can be used in the shallow sea and the deep sea, has the reliable sealing performance and the function of preventing misplug, and is applied to various underwater operation devices and used for transmitting the electrical signals.