An expansion card has at least one connector electrically coupled with at least one expansion slot of a server, and includes a shell defining at least one through slot, a main body, and a transmission element received in the shell. The transmission element includes a locating element, a connecting pole, and a fixing shaft. The connecting pole includes a head portion and a tail portion. The head portion defines a notch sleeving on the locating element. The tail portion extends outwards from the shell and defines a first hole. The fixing shaft is fixed on the shell and extends through the first hole. When the tail portion is pushed, the connecting pole rotates around the fixing shaft, the head portion drives the at least one connector to extends outwards or inwards from the at least one through slot, to electrically connected or disconnected to the at least one expansion slot.