An antenna testing device for testing an antenna assembled in a portable wireless communication device includes a data processing unit configured to receive signals from a CPU of the portable wireless communication device, a feedback unit, and a duplexer. The data processing unit sends the signals to the antenna by the feedback unit and the duplexer. The feedback unit feeds back mixed feedback signals mixed with signals leaked from the antenna to the data processing unit. The data processing unit judges whether the antenna is working properly according to the mixed feedback signals.