A receiver includes a CDR circuit, serial-to-parallel converter, and test module. The CDR circuit is for receiving the test signal groups inputted in series and following transmitting frequency of the test signal groups to obtain a clock signal, wherein the clock signal is used to provide an operational frequency of the receiver. The serial-to-parallel converter is for receiving the test signal groups outputted by the CDR circuit and converting the serially-inputted test signal groups into a plurality of test bytes outputted in parallel, wherein each of the test bytes has multi-bit of data. The test module is for receiving the test bytes and the clock signal and comparing two adjacent bytes of the test bytes to determine whether the two adjacent test bytes are completely the same.