A receiving device includes: a first signal processor, for receiving a radio frequency signal, and converting the radio frequency signal to generate a first signal, where the radio frequency signal includes a plurality of frames; a second signal processor, coupled to the first signal processor, for performing a Fourier transform operation on the first signal according to a synchronization signal to generate an output signal; a first filter, coupled to the first signal processor, for filtering the first signal to generate a second signal; and a synchronization detection circuit, coupled to the first filter, for detecting the second signal to generate the synchronization signal. The first signal includes a channel signal and at least a portion of neighboring channel signals from neighboring channels, and the output signal corresponds to the channel signal.