An electrical connector plug includes a casing an output/input port mounted having multiple upper terminals and multiple lower terminals, a trough defined between the upper terminals and the lower terminals, a circuit board inserted in the trough of the casing and having, a metal plate electrically connected to the ground terminal and a metal housing to entirely enclose the casing and to electrically connect to the metal plate such that the metal plate is able to transmit electromagnetic interference out via the metal housing.