An electrical connector for testing an electronic package, includes an insulative housing, an insulative sliding plate mounted upon the housing and moveable horizontally along a transverse direction, and a cover up-and-down movable relative to the housing in a vertical direction. The cover forms the actuating parts to contact the rollers of the sliding plate when the cover is downwardly pressed so as to not only urge the sliding plate to move horizontally in the transverse direction but also smoothly move downwardly to a lower position where the electronic package may be loaded upon the sliding plate in a zero insertion force condition with regard to the contacts.