The invention provides a method and a device of transmitting data. After frequency domain filtering and frequency domain mapping of various sub-band signals are executed, the data rates of the various sub-band signals are unified by the inverse Fourier transform, and therefore the filtering of the various sub-band signals is executed at a low sampling rate. Compared with time domain filtering of a prior art and the filtering of the various sub-bands required to be carried out at the high sampling rate according to the prior art, complexity of an F-OFDM transmitter is effectively reduced.