The invention relates to a socket combined device, in particular to an inwards-concave anti-electric-shock socket. The technical problems that in the using process, an existing socket is difficult to plug into and has potential safety hazards are solved. The inwards-concave anti-electric-shock socket comprises a socket body and a plug, wherein a groove is formed in the socket body, and jacks are formed in the bottom of the groove; the plug comprises a base, a boss and a metal plug pin, the boss is arranged on the front face of the base and matched with the groove, the metal plug pin is arranged at the top end of the boss, tail jacks are formed in the back face of the base of the plug and connected with the metal plug pin through an internal circuit, the side face of the boss is provided with a contact switch, a spring piece is arranged in each tail jack, and the contact switch is arranged to be matched with the spring pieces in an opened and closed mode. The socket body, the base and the boss are made of insulating materials. The inwards-concave anti-electric-shock socket is simple in structure, convenient and safe to use and low in production cost.