An electrical connector (1) for attaching an IC package to a circuit member includes a base (3) defining four side walls, a number of terminals receiving in the base, a cover (4) slidably mounted on the base and a lever (5) slidably moving the cover relative to the base. The base defines a plurality of grooves (31) extending from one side wall of the base to any other side wall of the base and one end of the groove is communicated with exterior space to decline the temperature of the terminals.