Onboard single-core electric connector assembly and plug thereof

The utility model relates to an onboard single-core electric connector assembly and a plug thereof. The onboard single-core electric connector assembly comprises the plug and a socket, the plug comprises a plug shell which is cylindrical, threads are arranged on a peripheral surface of the shell, a mounting hole is arranged on the plug shell, a contact part is fixedly inserted in the plug shell via the mounting hole, both of the two axial ends of the contact part extend out of the mounting hole and form plugging heads, and each plugging head comprises an inner plugging head used for matching with the socket in a plugged manner and an outer plugging head which is exposed outside a protecting shell covered on the outside of a printed board. The plug of the onboard single-core electric connector assembly greatly reduces abrasion between the socket on the printed board and the plug when the socket is connected with or disconnected from the external, the service life of the socket fixed on the printed board is pro