Abstract: A conductive sheet in a socket comprises a conductive sheet body having a conductive terminal on the rear end and two parallel conductive pins on the front end with an inserting slot formed therebetween. One of the conductive pins is provided with a recess, ring or projection. When the conductive sheet of the plug is inserted to the inserting slot of the conductive sheet in the socket, the recess, ring or projection provided on one conductive pin in the conductive sheet body corresponds to the hole of the conductive sheet of the socket, such the hole of the conductive sheet is uncovered. A latching means within the socket can enter the hole of the conductive sheet through the recess, ring or projection to lock the conductive sheet of the plug. In this way, the plug cannot be drawn from the socket.