A plug is disposed on a circuit board to be plug-connected to a socket, where the plug includes a metal housing and a spring pin, where the metal housing includes a first side plate and a second side plate that are oppositely disposed, and a first mating hole is formed on the second side plate; the spring pin is disposed on the second side plate along an insertion/removing direction of the plug, the spring pin includes a first connecting part and a bending part that is formed by bending and extending a first end of the first connecting part, a second end of the first connecting part is fastened inside the first mating hole, and the bending part is corresponding to the first mating hole and is separated from the second side plate.