The utility model relates to an electrical connecting device, include the footpath upwards outside -in in proper order each other the seat cover connected of socket joint, connect plug bush and fastener, the end -to -end connection of fastener has the tail -hood. The seat cover coordinates the section with the socket joint that connects the plug bush in, there is an annular step structure in the department at the seat cover inner wall to the cooperation has a seal structure at it and between connecing the bell end of plug bush, still is equipped with the 2nd seal structure between seat cover and the socket joint cooperation that connects the plug bush section, it has the shell of taking locking structure still to coordinate in the outside of seat cover, be equipped with the spacing second insulator through its internal face stair structure in proper order along the axial in connecing the plug bush to and can be equipped with a location structure and the 2nd location structure that can mutually support respectively at first insulator and the 2nd insulator to the first insulator of seat cover orientation extension, it is equipped with insulating block structure to connect between plug bush and the fastener. The utility model discloses an electrical connecting device can realize more reliable sealing between each component in the ware to can realize quick accurate location installation.