An electrical connector assembly is used for connecting to a chip module. The electrical connector assembly includes an electrical connector and a dust-proof cover. The electrical connector includes an insulative housing, a plurality of terminals and a shell covering the insulative housing. The insulative housing includes a second cavity for receiving the chip module. The shell defines an opening corresponding to the second cavity. The dust-proof cover includes a dust-proof portion covering the opening and a pair of inclined pushing portions protruding from the dust-proof portion to the second cavity. The dust-proof cover has a plurality of supporting portions for supporting the dust-proof portion. The supporting portions separate from the shell when the inclined pushing portion is pushed by the chip module, and the dust-proof cover separates from the electrical connector.