An electrical connector assembly includes: an electrical connector including a terminal module, a shielding shell enclosing the terminal module, an insulative cover enclosing the shielding shell, and a sealing member disposed at a front portion of the insulative cover; and an outer housing accommodating the electrical connector, wherein the insulative cover has a plurality of humps engaging an inner surface of the outer housing, and the sealing member is compressed between the front portion of the insulative cover and the inner surface of the outer housing.