An electrical connector includes an outer housing having two side arms extended from two opposite lateral sides of a holder base thereof and defining with the holder base a sliding space, a movable inner housing movable in and out of the sliding space and having two upright sidewalls at two opposite lateral sides of a bottom panel thereof and defining with the bottom panel a mating space, mating contact pins mounted at the bottom panel of the movable inner housing and partially suspending in the mating space, and a flexible connection interface electrically connected with the mating contact pins and extending out of the movable inner housing and the outer housing for connection to an external transmission interface.